PET Scan Uncovers Hidden Liver Malformation Behind Recurring Sepsis

A 73-year-old man with long-standing hidradenitis suppurativa suffered more than ten episodes of recurrent gram-negative septicaemia before an 18F-FDG PET/CT scan revealed that the true source of his bloodstream infections lay not in his diseased skin but in tiny, infected biliary hamartomas known as a von Meyenburg complex.

The case, published as an open-access report in EJNMMI Reports, illustrates both the diagnostic trap posed by comorbid infectious disease and the distinctive value of functional imaging when conventional modalities fail. Because the patient carried a well-recognised, chronically infected skin condition, repeated fever episodes had been attributed to his hidradenitis lesions or perianal and sebaceous ulcers, and he was discharged after short courses of antibiotics. Blood cultures intermittently grew Escherichia coli, but in several episodes no definite source was identified, and the events were labelled septicaemia of unknown origin.

von Meyenburg complex, or VMC, is a rare ductal plate malformation that typically presents as asymptomatic benign intrahepatic biliary microhamartomas. It arises when the smallest peripheral interlobular ductules fail to involute during embryonic development, leaving clusters of irregular, non-communicating ductules embedded in fibrous stroma. Ductal plate malformation exists on a spectrum: failure at the level of medium-sized intrahepatic ducts produces polycystic liver disease, while arrest at larger segmental or lobar ducts results in Caroli disease. VMC sits at the smallest end of that spectrum, and its tiny cysts, generally under five millimetres, are notoriously difficult to appreciate on unenhanced CT and remain subtle even with intravenous contrast, so they are often overlooked on routine cross-sectional imaging.

When secondarily infected, however, these benign lesions can become a cryptic reservoir of recurrent septicaemia, posing a substantial diagnostic challenge, particularly in patients with another obvious candidate source of infection. The authors note that bile stasis within these cystic dead spaces provides ideal conditions for bacterial colonisation, multiplication, micro-abscess formation and subsequent disruption and dissemination. Although the hamartomas are histologically non-communicating microbiliary dead spaces, case reports with tissue culture and microbiological support indicate that the infectious organisms, including Klebsiella pneumoniae, Klebsiella oxytoca and E. coli, originate from the cystic hamartomas themselves rather than from ascending cholangitis of bowel origin.

The patient’s most recent admission proved more refractory than earlier ones. Clinical notes described a mix of visible scarring and cutaneous sinuses, with suspicion of deep-seated micro-abscesses given his septic symptoms. Blood culture was again positive for E. coli, now resistant to amoxicillin-clavulanate and cotrimoxazole, agents that had been effective previously. Laboratory investigations showed persistent leukocytosis of 15 × 10⁹ per litre, an elevated C-reactive protein of 28 mg/L and a deranged liver profile, with alkaline phosphatase at 234 U/L, alanine aminotransferase at 82 U/L and aspartate aminotransferase at 90 U/L. Gamma-glutamyl transferase, total bilirubin, CA19-9 and CEA were all normal, and a rectal swab was negative for suspected pathogens.

Imaging at the referring hospital had already drawn a blank. 67Gallium whole-body planar scintigraphy showed only minimally heterogeneous liver activity, interpreted as within physiological distribution, with no focal tracer loculation to suggest an active infective or inflammatory focus on 24- and 48-hour images. That negative result, the authors observe, lent false reassurance that no hepatic infection was present. Because of the negative scan and ongoing diagnostic uncertainty, the patient was referred for 18F-FDG PET/CT, a functional imaging method established as useful in the investigation of fever of unknown origin.

The PET/CT protocol involved a six-hour fast with a blood glucose concentration of 5.8 mmol/L, followed by imaging 60 minutes after administration of 440 MBq of 18F-FDG on a Siemens Biograph Vision system, spanning from the base of skull to upper thigh. The CT component showed an enlarged liver, approximately 19.5 cm in craniocaudal dimension, with a smooth contour, uniform parenchymal density and a few scattered low-attenuation cystic lesions in both lobes without a specific distribution. The PET component, however, was decisive: patchy, heterogeneously increased FDG uptake throughout the cranial half of the liver formed a distinctive configuration the authors describe as an inverted pyramidal metabolic pattern, with a broad base along the subcapsular dome of the superior segments converging centripetally towards the peri-hilar and portal region. Some inner margins showed an infiltrative, prong-like appearance suggestive of ductal confluences, most prominent in the anteromedial dome of segment IVa and the lateral aspect of segments VIII and IVa. No other abnormal FDG-avid focus was identified in the gallbladder, extrahepatic bile ducts or anywhere else in the body.

This centripetal pattern, the authors explain, mirrored the dichotomous branching and coalescence of the intrahepatic biliary radicles, effectively providing a metabolic road map of the infected biliary tree from the smallest peripheral ductules to the larger segmental branches. Taken together with the clinical picture and the absence of dilated peripheral ducts on CT, the findings suggested a loculated infectious process affecting the small intrahepatic bile ducts, leading to the presumptive diagnosis of multiple infected biliary hamartomas complicated by micro-abscesses. Subsequent liver MRI with magnetic resonance cholangiopancreatography confirmed numerous T2-weighted hyperintense cystic lesions of varying sizes scattered throughout both hepatic lobes, the characteristic starry-sky pattern of diffuse biliary hamartomas, with heterogeneous contrast enhancement in scattered areas suggesting associated vascular shunts and mild dilatation of the intrahepatic portal ducts.

Yet even MRI could not settle the central question. The signal characteristics of VMC on T2-weighted sequences cannot with certainty distinguish sterile hamartomas from infected ones, because the lesions are too small to delineate the blurry, indistinct, irregular margins or transient peripheral enhancement that signal infection in macroscopic cysts. An enhanced mural nodule sign described in the literature is likewise neither specific nor sensitive enough for infected VMC. The diagnostic difficulty is such that the condition can present as image-negative ascending cholangitis, with severe sepsis and bacteraemia despite unremarkable ductal imaging. Susceptibility testing showed the patient’s E. coli isolate was sensitive to levofloxacin, and he was treated with intravenous levofloxacin 750 mg daily until clinical stabilisation, then oral levofloxacin 750 mg daily for two weeks after discharge.

A follow-up 18F-FDG PET/CT scan performed three weeks after completion of therapy demonstrated complete metabolic quiescence, with resolution of all previously documented intrahepatic hypermetabolic foci and disappearance of the inverted pyramidal distribution. Fever and septic parameters resolved in parallel. The authors caution that this is a single case report, and the diagnosis was supported by the concordance of imaging pattern, MRI morphology, microbiology and therapeutic response rather than by histopathology. Even so, they argue the case shows that FDG-PET/CT offers more than precise localisation of an occult infectious source: its metabolic pattern of involvement can suggest otherwise unsuspected morphological disorders, here revealing a rare congenital biliary condition as the hidden driver of recurrent sepsis that had been masked by a comorbid long-standing skin infection, and thereby guiding targeted antibiotic therapy and treatment monitoring.

Subject of Research: A case report on FDG-PET/CT diagnosis of infected von Meyenburg complex causing recurrent gram-negative septicaemia.

Article Title: Infected von Meyenburg complex causing recurrent gram‑negative septicaemia: the critical diagnostic role of FDG‑PET/CT in a patient with hidradenitis suppurativa

Article References: Ho, C. L., Chen, S., Wong, Y. H., Wu, K. K., Yip, Y., Lin, W. C., & Cheung, S. K. (2026). Infected von Meyenburg complex causing recurrent gram‑negative septicaemia: the critical diagnostic role of FDG‑PET/CT in a patient with hidradenitis suppurativa. EJNMMI Reports, 10(1), Article 40. https://doi.org/10.1186/s41824-026-00324-5

Image Credits: AI Generated

DOI: 10.1186/s41824-026-00324-5

Keywords: von Meyenburg complex, FDG-PET/CT, biliary hamartomas, septicaemia, hidradenitis suppurativa, ductal plate malformation, E. coli, MRI, MRCP, fever of unknown origin, case report, levofloxacin