The research, led by Ou Jia Emilie Wang and Quinn Stewart of the Faculty of Medicine at the University of British Columbia together with Jincheng Shi of the Division of Dermatology at The Ottawa Hospital and the University of Ottawa, was structured as a research letter but carries the weight of a large-scale audit. Two independent reviewers went through the figure collections of seven textbooks that are widely used in dermatologic surgery training, classifying every image by Fitzpatrick skin type and recording the associated diagnoses, procedures, and pigmentation findings. The Fitzpatrick scale, originally developed in 1975 to standardize responses to ultraviolet light, remains the dominant classification framework in dermatology despite well-documented limitations, and its six-category spectrum from type I, pale skin that always burns, to type VI, deeply pigmented skin that never burns, provided the study’s core metric.

The aggregate figure of 8.7 percent conceals a steeper drop-off in the subspecialties where visual pattern recognition matters most. Images depicting skin of colour were scarcest in Mohs micrographic surgery, the tissue-sparing technique for skin cancer removal, where they accounted for just 1.5 percent of figures. Facial reconstruction fared worst of all at 0.6 percent, followed by tumour imagery at 2.4 percent and wound care at 3.2 percent. These are precisely the domains in which surgeons must judge erythema, margins of inflammation, postoperative pigmentary change, and scarring patterns against a baseline that differs fundamentally from the pale skin that dominates the literature.

The clinical stakes of this visual deficit are not abstract. In highly pigmented skin, erythema may appear subtle or violaceous rather than bright red, making the early recognition of infection, flap ischemia, or allergic contact reactions considerably harder for a trainee who has never seen these presentations. Post-inflammatory hyperpigmentation and hypopigmentation, both common sequelae of surgical trauma in skin of colour, follow different courses and respond to different interventions than in lighter skin. Keloidal scarring, which occurs disproportionately in genetically darker skin, demands different surgical planning and adjunctive therapy. A recent systematic review of post-inflammatory hyperpigmentation treatment in skin of colour, cited by the authors, underscores how much of the evidence base itself is built on studies that under-recruit darker-skinned patients, compounding the textbook gap at every level of the educational pipeline.

The consequences extend into oncology. Acral lentiginous melanoma, the subtype that arises on the palms, soles, and nail apparatus, occurs at similar rates across populations but is disproportionately represented among people with darker skin, precisely because ultraviolet-driven melanomas are rarer there. Yet because educational imagery overwhelmingly shows melanoma on light skin, delayed diagnosis of acral lesions remains a documented driver of the survival gap, with population-level analyses from the United States showing worse outcomes for this subtype dating back decades. When a surgical textbook shows a trainee one hundred examples of melanoma and only a handful on brown or Black skin, the pattern-matching machinery of clinical judgment is calibrated accordingly.

The authors also flagged a structural problem that goes beyond simple counts: the near-total absence of standardized Fitzpatrick skin type labelling in the figures themselves. Without explicit labelling, readers cannot reliably identify which images depict which skin types, cannot gauge representation in any given chapter, and cannot use the images for calibrated self-testing. The lack of standardized annotation limits the educational value of whatever diverse imagery does exist and makes it difficult for publishers to track progress over time. In effect, the audit found both a quantitative shortfall and a qualitative infrastructure problem, since even the minority of skin-of-colour images are not systematically curated, tagged, or indexed for teaching purposes.

The new study builds on and extends a growing body of audit literature. A widely cited 2021 cross-sectional analysis published in the Journal of the American Academy of Dermatology by Alvarado and Feng found similar underrepresentation of dark skin in educational resources for common dermatologic conditions, helping to catalyze a wave of similar audits across journals, board review materials, and medical school curricula. The present analysis is notable for focusing specifically on dermatologic surgery, a procedural discipline in which the visual baseline matters not only for diagnosis but for intraoperative decision-making, and for its sheer scale, with more than three thousand figures classified by two independent reviewers rather than sampled or estimated.

The disparities documented in the textbooks mirror documented inequities in care. A 2025 comprehensive review of disparities in surgical site infection diagnosis and management in highly pigmented skin tones, cited in the study, describes how delayed recognition of infection in darker skin contributes to worse outcomes, while work on Mohs micrographic surgery in skin of colour has highlighted both the technical adaptations required and the scarcity of guidance available to surgeons. Educational materials are not the sole cause of such disparities, but they are a modifiable upstream factor: a resident who trains exclusively on images of light skin enters practice with a systematically skewed prior, and no amount of individual goodwill fully compensates for a curriculum that never showed them the relevant presentations.

The authors argue that deliberate, structured inclusion of skin of colour in surgical dermatology resources is necessary to support diagnostic accuracy and promote more equitable care. In practice, that means commissioning and licensing clinical photography that represents the full Fitzpatrick spectrum, standardizing skin type labelling across figures, and prioritizing the subspecialty areas where the deficit is most acute, particularly facial reconstruction and Mohs surgery. Some publishers and educational platforms have begun such initiatives in response to earlier audits, but the new data suggest that the field’s foundational textbooks, the reference works against which trainees are examined, have not yet caught up. The study’s authors received no external funding for the analysis and declare no competing interests.

As dermatology confronts a demographic reality in which the majority of the global population has pigmented skin, and as populations in North America and Europe grow increasingly diverse, the visual canon of the specialty is under pressure to change. The message of this audit is quantitative and unambiguous: out of 3,334 images across seven authoritative textbooks, fewer than three hundred showed the skin types carried by most of humanity. Closing that gap will require more than good intentions; it will require the same systematic curation, labelling, and editorial accountability that the field applies to its evidence base, so that the next generation of surgeons learns to read every skin the way it has long been trained to read one.

Subject of Research: Representation of skin of colour in dermatologic surgery textbook imagery

Article Title: Skin of colour representation in dermatologic surgery textbooks: an image analysis

Article References: Wang, O. J. E., Stewart, Q., & Shi, J. (2026). Skin of colour representation in dermatologic surgery textbooks: an image analysis. Archives of Dermatological Research, 318(1), Article 385. https://doi.org/10.1007/s00403-026-04853-8

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04853-8

Keywords: dermatologic surgery, skin of colour, Fitzpatrick skin type, medical education, health equity, Mohs surgery, textbook imagery, facial reconstruction, post-inflammatory hyperpigmentation, diagnostic disparity, dermatology training, wound care

The study, led by Federico Venturi and Emi Dika with colleagues in Bologna and Ancona, focused specifically on recurrent lentigo maligna of the face. Adults who had previously undergone complete surgical excision of a facial lentigo maligna and then developed a histologically confirmed recurrence at the same site within 24 months were enrolled. Recurrence was defined strictly: a new lesion had to arise after a documented disease-free interval and be verified by biopsy or excision. This is a notoriously difficult patient population, because the previous surgery leaves fibrotic tissue that both conceals subclinical tumor strands and complicates any attempt to judge margins by eye. The researchers compared two management pathways in a prospective, single-center design: one group of 21 patients had their surgical margins mapped preoperatively with handheld reflectance confocal microscopy, while a control group of 33 patients was planned using standard clinical and dermoscopic assessment alone.

Reflectance confocal microscopy is a noninvasive optical technique that uses a low-power laser focused on a single point within the skin and measures the light scattered back from tissue structures. By scanning the beam laterally and at different depths, the device builds grayscale horizontal images, sometimes described as optical sections, at near-cellular resolution down to roughly the depth of the superficial dermis. In the hands of a trained reader, this makes it possible to identify the hallmark features of lentigo maligna in vivo: proliferation of atypical, bright, round and dendritic cells along the basal layer of the epidermis, irregular honeycomb or disordered patterns of the epidermis, and pagetoid spread of melanocytes upward through the epidermal layers. Crucially, the handheld version of the device trades some of the stability of traditional benchtop confocal systems for portability, allowing clinicians to examine patients directly in the clinic or at the bedside and to probe skin anywhere on the body, including curved facial contours that a fixed microscope cannot easily reach.

The Bologna team used a standardized adhesive tape technique to translate confocal findings into a practical surgical map. After identifying the outermost confocal extension of the tumor, the clinicians marked the skin and applied adhesive suture tapes bearing grid markings, creating a durable record of the mapped boundary that could be handed directly to the surgeon. This approach, which the group has refined in earlier work on non-melanoma skin cancers of the head and neck, effectively converts a live optical examination into a physical template for excision. In the study, surgical margins were subsequently verified by permanent-section histopathology in every case, meaning the accuracy of the preoperative maps could be judged against the gold standard of laboratory examination of the removed tissue.

The results were striking. Complete margin clearance in a single surgical stage was achieved in 85.7 percent of patients in the confocal-mapping group, compared with 60.6 percent of those planned conventionally. In other words, roughly nine out of ten patients whose tumors had been mapped with the handheld device left the operating room after one procedure, while nearly four in ten of the conventionally planned patients needed additional excisions to reach clear margins. Each repeat excision carries costs beyond the operating schedule: more anesthesia, more scarring on cosmetically sensitive facial skin, longer healing times, and greater patient anxiety. Avoiding staged procedures is therefore one of the most meaningful outcomes a preoperative planning tool can deliver.

The size of the surgical defects told a similar story. The mean defect diameter in the confocal group was 1.7 centimeters, with a standard deviation of 0.6, versus 2.4 centimeters, with a standard deviation of 0.8, in the clinical group, a difference that reached statistical significance at p less than 0.01. Smaller defects matter enormously on the face, where the availability of local tissue governs what kind of closure is possible. This translated directly into the study’s primary outcome: only 28.6 percent of patients in the confocal-mapped group required invasive reconstructive procedures, such as flaps or grafts, compared with 60.6 percent of the conventionally planned group, a reduction that was statistically significant at p equal to 0.009. The authors describe this as downstaging the surgical repair, a phrase that captures the practical benefit: the same tumor can be managed with a simpler, more conservative operation when its boundaries are known in advance.

Perhaps the most important question for any technique that narrows surgical margins is whether it compromises cancer control. On this point the study was reassuring, at least over the short follow-up window. Local recurrence rates at 12 months were low and statistically comparable between the two groups, at 4.7 percent in the confocal group and 6.1 percent in the clinical group. The investigators emphasize that the confocal approach did not cut corners oncologically; rather, it delineated the subclinical extension of the tumor more accurately than visual inspection, so the excision could be tailored to the disease rather than to a generous default margin. Because lentigo maligna can recur years after treatment, longer follow-up will be needed to confirm that the early equivalence holds, and the authors themselves frame the recurrence data as short-term oncologic control.

The findings arrive amid a growing body of evidence supporting confocal margin mapping for this tumor type. Previous prospective work has shown that confocal delineation of lentigo maligna margins correlates well with staged excision histology, and a 2025 systematic review and meta-analysis concluded that reflectance confocal microscopy is a reliable tool for margin assessment in lentigo maligna melanoma. A Dutch group has gone further, reporting the successful implementation of handheld confocal microscopy as a standard of care in the surgical management of lentigo maligna at their head and neck center. The Bologna study adds a specific and clinically valuable data point: the technique works even in the hardest scenario, recurrent disease at a previously operated site, where scarring has traditionally made margin assessment least reliable.

The broader significance of the study lies in what it suggests about the future of skin cancer surgery. Noninvasive imaging modalities, including reflectance confocal microscopy, optical coherence tomography, and dermoscopy-guided high-frequency ultrasound, are increasingly being tested as ways to plan excisions of skin cancers before the patient reaches the operating table. For lentigo maligna in particular, where histologic margins routinely exceed clinical margins by wide margins, the economic and human calculus is compelling: a handheld device examination in clinic is far cheaper and less burdensome than a second operation, a flap reconstruction, or a prolonged staged excision process. The adhesive tape mapping method also lowers the barrier to adoption, since it requires no exotic materials and integrates with existing surgical workflows.

Limitations remain, and the authors are careful about them. The study was single-center, the two groups were not randomized in the traditional sense, and the confocal cohort was smaller than the comparison cohort, all of which counsel caution before declaring a new standard of care. Reader expertise is also a genuine constraint, because interpreting confocal images of sun-damaged facial skin requires training and experience, and false negatives at the margin edge remain a risk. Still, the direction of the evidence is consistent across multiple independent groups, and the Bologna data address the scenario where the clinical need is most acute. For elderly patients with recurrent facial lentigo maligna, many of whom have limited tissue reserve and significant comorbidities, a technique that converts a major facial reconstruction into a modest excision is not a small technical refinement. It is the difference between a procedure that reshapes a nose or cheek and one that does not, achieved with a laser the size of a large pen and a strip of adhesive tape.

Subject of Research: Pre-surgical margin mapping of recurrent facial lentigo maligna using handheld reflectance confocal microscopy

Article Title: Pre-surgical mapping of recurrent lentigo maligna of the face with handled confocal microscopy: a useful tool to downstage surgical repair

Article References: Venturi, F., Veronesi, G., Magnaterra, E., Scotti, B., Baraldi, C., & Dika, E. (2026). Pre-surgical mapping of recurrent lentigo maligna of the face with handled confocal microscopy: a useful tool to downstage surgical repair. Archives of Dermatological Research, 318(1), Article 402. https://doi.org/10.1007/s00403-026-04895-y

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04895-y

Keywords: lentigo maligna, melanoma, reflectance confocal microscopy, handheld confocal microscopy, surgical margin mapping, dermatologic surgery, facial reconstruction, recurrent melanoma, preoperative imaging, skin cancer, dermoscopy, Mohs surgery

The research, conducted on computed tomography images of 409 living individuals, 226 males and 183 females, represents one of the largest datasets assembled for this purpose in a North Indian population. The choice of imaging modality matters enormously. Unlike studies based on cadavers, where soft tissue shrinks and distorts after death, CT scans capture the true relationship between the bony framework and the overlying soft tissues in living people. The authors measured seventeen metrical parameters, spanning soft tissue depths, linear distances, and angles, and then constructed regression models to predict the various dimensions of the external nose from measurements that can be taken directly on a skull.

The logic of regression-based prediction is central to the method. In forensic facial approximation, an artist or anthropologist needs to know, for example, how far the tip of the nose, the pronasale, projects forward from a given bony landmark, or how wide the nostrils will be relative to the width of the nasal aperture. Traditional guidelines, some dating back to the pioneering work of Mikhail Gerasimov in the mid-twentieth century, offered rough anatomical rules of thumb. Subsequent decades brought a wave of proposed relationships between hard and soft tissue dimensions, tested and debated in populations from Scotland to Brazil, Korea, and Japan. The persistent problem is population specificity: nasal form varies substantially across human groups, shaped in part by climatic adaptation, and a prediction equation derived from one population may mislead when applied to another.

By building their models from CT data of living North Indian adults, Singh and Purkait provide equations tailored to the population most likely to be encountered in their medico-legal context. The seventeen parameters include soft tissue depths at key landmarks, which allow the reconstruction artist to place the nasal tip, the alar margins, and the bridge with quantified confidence rather than guesswork. Regression analysis, when its assumptions are properly tested, offers a defensible statistical bridge between what the skull preserves and what the living face displayed. Each predicted dimension narrows the space of possible noses, and by extension, the space of possible identities.

But metrics alone cannot capture everything that makes a face recognizable. The study therefore went beyond measurement, cataloguing forty morphological attributes of the nose, features such as the shape of the bridge, the form of the tip, and the character of the nostrils, to identify which nasal features occur most frequently in the studied population and, crucially, which bony traits tend to accompany which soft tissue traits. This dual approach yields two distinct working methods, each suited to a different state of the recovered skull.

The first method, called the most frequent nasal features method, is designed for the worst-case scenario: a skull in which the fragile nasal bones are missing entirely. In such cases, the reconstruction relies on the population-level frequency of nasal features, essentially building a statistically typical nose consistent with the surviving anatomy of the midface. The second method, the characteristic association method, applies when the nasal bones are partially broken or intact. Here the reconstruction becomes more individualized, because specific configurations of the bony nose are associated with characteristic configurations of the soft tissue nose. A particular shape of the nasal aperture or bridge, in other words, carries information about the overlying soft form that a fully denuded skull cannot provide.

The workflow that emerges from the study is a hybrid one. The nasal framework is first constructed using the metrical parameters, establishing the quantitative skeleton of the soft nose: its projection, width, and height, anchored to the bony landmarks. The reconstruction is then refined morphologically, adjusting the shape of the tip, the alae, and the contour of the bridge to match the most probable features or the characteristic associations indicated by the bone. This layering of quantitative prediction and morphological judgment is designed to increase the likelihood that the reconstructed face resembles the antemortem face, which is the ultimate measure of success in facial approximation.

The significance of the work lies partly in its scale and partly in its pragmatism. Previous systematic reviews of nasal prediction techniques have catalogued dozens of methods, from simple proportion rules to three-dimensional statistical shape models derived from cone-beam CT. Many were tested on small samples or on populations far removed from the case at hand. Studies in Korean, Japanese, Brazilian, and Turkish populations have each produced population-specific databases of facial soft tissue thickness and nasal dimensions, underscoring that no single universal formula exists. The Indian subcontinent, with its enormous population and substantial medico-legal caseload, has been comparatively underrepresented, and the new study adds a substantial, ethically approved dataset to the global record.

The method also reflects a broader shift in forensic anthropology from two-dimensional profile estimation toward fully three-dimensional reconstruction. Early techniques predicted nose projection in profile only, leaving the artist to improvise the width and the shape of the tip. Three-dimensional imaging now allows every dimension to be modeled simultaneously, and the resulting reconstructions can be rendered digitally, compared against missing-persons photographs, and adjusted iteratively. The authors’ combination of seventeen metrical predictors with forty morphological attributes is an attempt to systematize what has long been an art guided by incomplete science, giving practitioners a repeatable protocol rather than a set of divergent personal heuristics.

For the families of missing persons, the stakes of this technical work are profoundly human. A reconstructed face displayed in the media may be the last realistic chance that someone recognizes a lost relative, and the nose sits at the center of that recognition. By quantifying the relationship between the skull and the soft tissue nose in a large living sample, and by offering clear decision rules for skulls in different states of preservation, Singh and Purkait have given forensic practitioners a more rigorous toolkit for turning anonymous remains back into a person with a face, a name, and, ultimately, an identity.

Subject of Research: Forensic facial reconstruction of the nose from skull measurements

Article Title: A proposed morphological and metric method for three-dimensional nasal reconstruction

Article References: Singh, S., & Purkait, R. (2026). A proposed morphological and metric method for three-dimensional nasal reconstruction. International Journal of Legal Medicine. https://doi.org/10.1007/s00414-026-03959-y

Image Credits: AI Generated

DOI: 10.1007/s00414-026-03959-y

Keywords: forensic anthropology, facial reconstruction, nose prediction, computed tomography, regression models, soft tissue depth, nasal aperture, morphological traits, North Indian population, International Journal of Legal Medicine, proposed, morphological

The research, published in the International Journal of Legal Medicine, was led by Sushil Kumar Battan and colleagues at the Postgraduate Institute of Medical Education and Research in Chandigarh together with collaborators at Chandigarh University. The team carried out a retrospective cross-sectional analysis of computed tomography scans from 1,972 individuals aged between 18 and 80 years, all drawn from a northwestern Indian population. Rather than relying on the mean tissue depths that have dominated facial reconstruction practice for decades, the researchers measured both total craniofacial soft tissue thickness and the subcutaneous fat layer thickness separately, at 73 standardized craniofacial landmarks.

The distinction matters because the total thickness at any point on the face is not a single uniform material. It is a composite of skin, muscle, fascia, glands and fat, and only the subcutaneous fat component changes dramatically with age, sex, nutrition and body composition. Most existing reference tables, including large in vivo databases assembled for European populations, collapse all of these layers into a single number. By separating the adipose from the non-adipose contribution, the Indian dataset offers reconstructers a two-parameter description of facial architecture, which in principle allows far more nuanced modeling of how a face would have looked in life.

Technically, the measurements were extracted from CT imaging, which provides the millimeter-scale resolution needed to delineate the boundary between the bone, the deeper soft tissues and the subcutaneous fat plane. The statistical analysis combined classical tools with machine learning. Descriptive statistics established the baseline distributions at each landmark, independent t-tests quantified differences between the sexes, analysis of variance tested variation across age groups, and Pearson correlation assessed how tightly the two thickness measures track each other. On top of this, the team trained regression and machine learning algorithms to predict tissue thicknesses and to evaluate how well different variables explain the observed variation.

The results confirm that total soft tissue thickness consistently exceeds fat layer thickness at every one of the 73 landmarks, underscoring that a substantial portion of facial volume comes from muscle and other non-adipose structures. At the level of individual landmarks, the correlation between the two measures was strong, with a coefficient of determination of roughly 0.785, meaning that about three quarters of the landmark-level variation in total thickness can be accounted for by the fat layer alone. Interestingly, that relationship weakens dramatically when data are aggregated by age group, where the correlation drops to about 0.143. This suggests that while fat is a dominant driver of thickness at any given anatomical point, age-related changes in the two layers follow partially independent trajectories, likely reflecting muscle atrophy and connective tissue remodeling that proceed on different schedules from fat redistribution.

Sexual dimorphism emerged clearly in the data, with males showing higher values than females across the landmark set, although the effect sizes were small. That combination of statistical significance and modest magnitude is a familiar pattern in facial anthropometry and carries a practical warning for forensic practitioners: knowing the sex of a skull helps narrow the expected tissue depths, but it does not remove the need for population- and age-appropriate reference values. The age analysis revealed a classic increase-peak-decline pattern, with thickness measurements rising through early adulthood, reaching a maximum in middle adulthood and then declining in older age groups, mirroring the well-documented trajectory of facial fat compartments and the progressive resorption of the underlying facial skeleton.

One of the most striking findings concerns symmetry. When the researchers compared measurements taken on the right and left sides of the same faces, they found an extremely high correlation, with a coefficient of determination of 0.992. For forensic facial approximation, this is reassuring news, because it means that reference values collected on one side of the head can be applied to the other with negligible loss of accuracy, and that genuine bilateral asymmetry in soft tissue depth is rare enough to be treated as an exception rather than a rule in reconstruction work.

The artificial intelligence component of the study is where the project pushes furthest beyond conventional practice. The team compared machine learning models against standard linear regression and found that the best-performing algorithms, particularly a Random Forest model, achieved coefficients of determination exceeding 0.90 within the dataset, outperforming conventional approaches and showing limited systematic bias. Random Forest methods work by building an ensemble of decision trees, each trained on random subsets of the data and features, and averaging their predictions; this makes them well suited to capturing the nonlinear interactions between age, sex, landmark position and body composition that govern facial tissue thickness, interactions that a single linear equation cannot represent.

The authors are careful to flag the central limitation of these results: the models demonstrated strong within-dataset performance, but independent external validation is required before the predictions can be trusted on new populations or imaging systems. A model that achieves an R-squared above 0.90 on the data it was trained and tested on may still degrade when confronted with scans from a different scanner, a different ancestry group or a different body mass distribution. This caution reflects a broader lesson from the application of machine learning in medical imaging, where promising internal metrics have repeatedly failed to translate without rigorous external testing.

Even with that caveat, the study delivers something the forensic community has long needed: a large, CT-derived, population-specific reference database for a northwestern Indian population, one of the most populous regions of the world that has been underrepresented in facial reconstruction literature. Most established tissue depth tables were built from cadaver measurements or smaller imaging samples of European and East Asian subjects, and applying them to other populations introduces systematic error into reconstructed faces. By integrating total soft tissue thickness and fat layer thickness across 73 landmarks, quantifying sex and age effects, and demonstrating near-perfect bilateral symmetry, the Chandigarh team has produced a foundation for more accurate, data-driven facial approximation. As AI-guided craniofacial reconstruction systems mature, datasets of this kind will be the raw material that determines whether a reconstructed face becomes a recognizable likeness or just an anatomical guess.

Subject of Research: AI-based CT measurement of craniofacial soft tissue and fat thickness for forensic facial reconstruction in a northwestern Indian population

Article Title: Artificial intelligence -based modeling and comparative evaluation of craniofacial soft tissue and subcutaneous fat thickness using ct imaging for forensic identification in a northwestern indian population

Article References: Battan, S. K., Sharma, M., Garg, M., Singh, P., verma, P., & Singla, N. (2026). Artificial intelligence -based modeling and comparative evaluation of craniofacial soft tissue and subcutaneous fat thickness using ct imaging for forensic identification in a northwestern indian population. International Journal of Legal Medicine. https://doi.org/10.1007/s00414-026-04000-y

Image Credits: AI Generated

DOI: 10.1007/s00414-026-04000-y

Keywords: forensic science, facial reconstruction, craniofacial soft tissue thickness, subcutaneous fat, computed tomography, artificial intelligence, machine learning, sexual dimorphism, aging, bilateral symmetry, forensic identification, population-specific database

The three methods under scrutiny represent some of the most widely used guidelines in the field. The first is the so-called three-fifths rule, which holds that the width of the soft nose equals the maximum width of the bony nasal aperture divided by 0.6. The second, proposed by Davy-Jow and colleagues in 2012, claims that the contour of the superior nasal aperture mirrors the shape of the nasal tip in a one-to-one fashion when the head is rotated dorsally by about sixty degrees from the Frankfurt horizontal plane. The third is a revised version of the famous two-tangent method attributed to Mikhail Gerasimov, the Soviet pioneer of facial reconstruction, in which the tip of the nose, the pronasale, is located at the intersection of a line projected from the distal tip of the nasal bones and a second line projected from the floor of the nasal aperture.

The study’s raw material was a set of full-head CT scans of embalmed body donors to the University of Queensland anatomy program, comprising 53 males and 39 females aged between 51 and 100 years. The scans were acquired with a 16-slice Siemens Biograph helical CT at a slice thickness of just 0.75 millimeters, using settings of 130 kilovolts and 220 milliamperes-seconds. Decedents were deliberately chosen rather than living volunteers because the thin-slice protocol needed for such anatomical clarity would deliver radiation doses far above what is permissible for clinical scans of living people, and because donors remain perfectly still during acquisition, eliminating the blurring caused by breathing, heartbeat and muscle tone. Surface meshes of both skull and face were exported from the scans into Blender for measurement and analysis, with bone segmented at Hounsfield unit thresholds of 300 to 400 and soft tissue between minus 200 and minus 350.

Because the nose is an extremely pliable structure that loses its elastic recoil after death, the researchers carefully screened every subject for even the slightest compression or deformation of the nasal tissues. This screening meant that different subsets of the original 92 subjects were used to test each method: 63 individuals for the nose width rule, 31 for the nasal tip shape method, and 43 for the pronasale position technique. The authors argue that this conservative approach ensured that only the highest fidelity data entered each analysis, even though it reduced sample sizes.

The results for nose width were, on balance, encouraging but nuanced. The mean ratio between nasal aperture width and soft nose width across the 63 subjects came out at 0.614, remarkably close to the 0.6 value of the three-fifths rule, confirming that the guideline captures the central tendency of the population well. Mean errors were small, at 0.7 millimeters for males and 1.5 millimeters for females. However, the standard errors of the estimate were around 4 millimeters for both sexes, and the correlation between bony and soft tissue widths was a modest 0.32. In practical terms, this means that while the rule is accurate on average, individual predictions can be substantially wrong, with some people’s noses deviating widely from the population mean. The authors note that this finding echoes earlier work: Rynn and colleagues reported a mean error of only 0.4 millimeters in a 2010 CT study, while Ryu and colleagues found a correlation of 0.35 in South Koreans, closely matching the present result.

The nasal tip shape test delivered a more sobering verdict. Using geometric morphometric techniques, the researchers extracted 31 landmarks along both the bony curve of the superior nasal aperture and the soft tissue curve of the nasal tip for each of the 31 screened subjects, then compared the curves after Procrustes registration, which removes differences in position, rotation and scale. The resulting Procrustes distance of 0.24 indicates a moderate but real shape mismatch. Mean point-to-point differences between the curves averaged 4.0 millimeters, and visual inspection of the mean curves showed that the hard tissue contour is considerably more peaked at its apex than the soft tissue curve, which is flatter and more gently rounded. This is the first empirical cross-validation of the Davy-Jow method, and the authors conclude that the assumption of a direct one-to-one correspondence between the bony aperture and the nasal tip outline should be treated with considerable skepticism.

The pronasale position test focused on Gerasimov’s revised two-tangent method, incorporating clarifications published by Ullrich and Stephan in 2011 based on archival research into Gerasimov’s actual practice. These clarifications revealed that Gerasimov used only the very last 1 to 2 millimeters of the nasal bone to set the upper tangent, not the last third as his published instructions stated, and that the lower tangent was drawn not from the nasal spine but from the floor of the nasal aperture beside the vomer bone. In a methodological advance, the Queensland team abandoned the traditional practice of eyeballing these tangent lines and instead used Blender’s mesh editing tools to select triangular faces of the skull tessellation, calculate the mean surface normal for each region of interest, and attach tangents to the resulting quantitatively defined planes. This removed subjective judgment from a step that has always been performed by visual estimation.

Even with this precision, the two-tangent method showed substantial errors. The mean x-coordinate error was 2.2 millimeters, indicating that the estimated nose tip sits too far forward, while the mean y-coordinate error was minus 6.2 millimeters, indicating it sits too far down. The Euclidean distance between estimated and true pronasale positions averaged 8.3 millimeters, with a standard error of the estimate of 10 millimeters. These figures closely replicate those of Maltais Lapointe and colleagues, who in 2016 validated the revised interpretation using CT scans of 66 subjects and concluded that the error of any version of Gerasimov’s method is too high for reliable identification work. The present study also revealed large intra-observer variability in placing the estimated pronasale, with a technical error of measurement of 4.0 millimeters on the x-axis, underscoring the method’s limited repeatability even when tangents are defined numerically.

Rather than simply discarding the flawed methods, the authors propose a statistical remedy known as calibration-in-the-large. By applying the sign-reversed mean errors as correction factors, systematic biases in the estimation models can be removed. For the two-tangent method, translating the estimated pronasale by minus 2.2 millimeters in x and plus 6.2 millimeters in y reduced the standard error of the Euclidean distance from 10.0 to 2.5 millimeters in the study’s own training data, a fourfold improvement, and from 10.1 to 8.3 millimeters in the independent dataset of Maltais Lapointe and colleagues. Similar corrections of minus 0.7 millimeters for males and minus 1.5 millimeters for females were proposed for the nose width rule. The authors caution that these calibrations are derived from training data and may suffer some overfitting, so their true utility must be confirmed in future out-of-group samples. Nonetheless, the study marks an important step toward a more honest accounting of facial approximation: a field that can now quantify, in millimeters, exactly how much its oldest rules bend the truth, and begin to correct them.

Subject of Research: CT-based validation of nose width, nasal tip shape and pronasale position estimation models for craniofacial identification

Article Title: Nose-skull relationships for craniofacial identification: computed tomography (CT) assessment of nose width, nasal bridge shape & pronasale position

Article References: Xue, Y. W., & Stephan, C. N. (2026). Nose-skull relationships for craniofacial identification: computed tomography (CT) assessment of nose width, nasal bridge shape & pronasale position. International Journal of Legal Medicine. https://doi.org/10.1007/s00414-026-04009-3

Image Credits: AI Generated

DOI: 10.1007/s00414-026-04009-3

Keywords: craniofacial identification, facial approximation, forensic anthropology, nose width, pronasale position, nasal aperture, computed tomography, Gerasimov two-tangent method, geometric morphometrics, facial reconstruction, calibration-in-the-large, International Journal of Legal Medicine