The case, reported by a team at Nemours Children’s Hospital in Orlando and the University of Central Florida College of Medicine in the journal Frontiers in Urology, describes a benign paratesticular myofibroblastic lesion, a spindle cell tumor so rare in children this young that isolated paratesticular presentations have not previously been documented in the literature. To appreciate why this matters, it helps to understand the landscape. Prepubertal testicular and paratesticular neoplasms account for roughly 1 to 2 percent of all solid tumors in children, with an estimated incidence of 0.5 to 2 cases per 100,000. These tumors show a peak incidence at approximately 2 years of age, and up to 60 percent present before that age is reached. The toddler in this report sat squarely at that epidemiological peak.

Crucially, the odds favored benignity from the start. Unlike intratesticular masses, which in children are more frequently malignant, the majority of paratesticular lesions, meaning those arising outside the testicular parenchyma itself, are benign. Registry studies suggest that approximately 40 percent of childhood testicular tumors are benign, and among benign paratesticular entities, fibrous pseudotumor ranks as the third most common after adenomatoid tumor and lipoma. But fibrous pseudotumor has been described almost exclusively in adults, with pediatric cases exceptionally rare beyond isolated case reports. Inflammatory myofibroblastic tumors of the paratesticular region, another key differential consideration, have been reported predominantly in adolescents. Myofibromas, the most common fibrous tumor of childhood overall, are extremely rare in the testis, with only three previously reported pediatric cases, and paratesticular soft tissue involvement specifically had not been reported at all.

The initial evaluation began with scrotal ultrasound and Doppler imaging, which demonstrated a 1.2-centimeter isoechoic extratesticular lesion in close proximity to the head of the right epididymis, the coiled structure atop the testicle where sperm mature. The lesion showed internal vascularity, meaning blood vessels ran through it, while both testes appeared normal in size and echotexture without intratesticular masses. Arterial and venous blood flow to both testes was preserved. A trace right hydrocele, a small fluid collection around the testicle, was noted. The differential diagnosis at that stage included a torsed appendix testis, a common benign event in boys, and less likely a supernumerary testicle, an extra testicular structure. Follow-up imaging was recommended.

Serum tumor markers provided the next layer of evidence. Alpha-fetoprotein, beta-human chorionic gonadotropin, and lactate dehydrogenase, the classic biochemical fingerprints of germ cell tumors and other malignancies, were all within normal limits. Over the ensuing three months, serial scrotal ultrasounds consistently demonstrated a stable, well-circumscribed extratesticular mass measuring approximately 0.9 to 1.1 centimeters adjacent to the superior aspect of the right testicle, with internal vascularity and echogenicity similar to testicular tissue. At times the lesion displayed a central echogenic focus suggestive of a mediastinum-like structure, raising consideration for a supernumerary or bilobed testicle. No interval growth or concerning radiographic changes appeared, and bilateral testes remained normal with symmetric blood flow.

Despite the reassuring stability and negative markers, one shadow could not be dispelled: malignancy, particularly paratesticular rhabdomyosarcoma, a malignant spindle cell tumor of skeletal muscle origin that is among the most feared paratesticular cancers in young boys, could not be definitively excluded on imaging alone. Historically, this diagnostic ambiguity has carried a heavy price. Myofibroblastic lesions may mimic malignant tumors clinically and radiographically, and that mimicry has led to unnecessary radical orchiectomy, the complete surgical removal of the testicle, in cases that turned out to be benign. The surgical team, the pathologists, and the family weighed continued surveillance against surgical exploration in a multidisciplinary setting. Given the persistent uncertainty about pathology and the parents’ concern, the decision was made to proceed with inguinal exploration with intraoperative frozen section analysis.

The operative plan reflected standard oncologic caution. The child was placed supine under general anesthesia, and a right inguinal incision was made. The spermatic cord was isolated and proximal control established, the same maneuver performed when malignancy is suspected, ensuring that if cancer were found the cord could be secured before any tumor manipulation. The right testis was delivered through the incision, revealing a firm extratesticular mass at the superior pole within the tunica vaginalis, the serous membrane surrounding the testis, in close proximity to the spermatic cord. Careful dissection showed the lesion attached by a thick stalk to the tunica albuginea, the dense fibrous capsule of the testis itself. The stalk was excised with a 2- to 3-millimeter margin of tunica albuginea, and hemostasis was achieved with bipolar cautery.

Then came the pivotal moment. The gross specimen revealed a well-circumscribed, firm white nodule with a white, fibrous cut surface. Frozen section analysis, a technique in which fresh tissue is rapidly frozen, sliced thin, stained, and examined under a microscope within minutes while the patient remains anesthetized, demonstrated bland spindle cells without features of malignancy. Bland is the pathologist’s term for cells that look uniform and orderly rather than pleomorphic and aggressive. Following discussion with the family, testis-sparing management was pursued: the testis was returned to the scrotum, the incision closed, and the child discharged home in stable condition the same day.

Permanent histopathology confirmed the frozen section findings with greater precision. Examination demonstrated a well-circumscribed nodule within the paratesticular soft tissue composed of bland spindle cells arranged in a loose collagenous stroma, with associated dystrophic calcifications, calcium deposits that form in damaged or degenerating tissue rather than in bone. Immunohistochemistry, the technique that uses antibodies to detect specific proteins in tissue sections, showed the tumor cells positive for smooth muscle actin, a marker of myofibroblastic and smooth muscle differentiation, and negative for desmin, myogenin, MyoD1, beta-catenin, and S100. The negativity for desmin and the muscle regulatory proteins myogenin and MyoD1 argued against rhabdomyosarcoma, while the negativity for S100 excluded neural and melanocytic lesions. Anaplastic lymphoma kinase immunostaining was also negative, which excluded inflammatory myofibroblastic tumor, an entity that is typically ALK-positive and characterized by inflammatory infiltrates. The combined profile supported a diagnosis of benign myofibroblastic lesion, consistent with a fibrous pseudotumor.

The recovery was uneventful. At postoperative follow-up the child had returned to normal activities with normal oral intake, urination, and bowel movements, and experienced no significant postoperative pain. Scrotal ultrasound at three months was unremarkable, with no evidence of recurrence, and he will continue surveillance with annual ultrasound for at least five postoperative years. The authors acknowledge the limits of a single-patient report: generalizability is constrained, broader molecular profiling was not performed, and follow-up duration remains relatively short. Yet the case carries a message that resonates far beyond one toddler. Benign paratesticular myofibroblastic lesions should be considered in the differential diagnosis of paratesticular spindle cell lesions in prepubertal children, and accurate histopathologic evaluation supported by immunohistochemistry is essential to rule out inflammatory myofibroblastic tumor. When imaging, tumor markers, and rapid intraoperative pathology converge, surgeons can spare a testicle that an earlier era might have removed, preserving not just an organ but the child’s future fertility potential and hormonal function.

Subject of Research: Pediatric urology case report of a rare benign paratesticular spindle cell tumor

Article Title: Paratesticular myofibroblastic lesion in a prepubertal child: a case report of a rare spindle cell tumor with testis-sparing management

Article References: Sheiber, J., Nguyen, J., Smith, M., Bajaj, M., Seth, A., Ellsworth, P., & Cai, P. Y. (2026). Paratesticular myofibroblastic lesion in a prepubertal child: a case report of a rare spindle cell tumor with testis-sparing management. Frontiers in Urology, 6, Article 1866045. https://doi.org/10.3389/fruro.2026.1866045

Image Credits: AI Generated

DOI: 10.3389/fruro.2026.1866045

Keywords: pediatric urology, paratesticular tumor, myofibroblastic lesion, frozen section, testis-sparing surgery, spindle cell tumor, case report, Paratesticular, myofibroblastic, lesion, prepubertal, child