Differential Diagnosis of a Pediatric Ovarian Tumor: The Pitfall of Juvenile Fibrosarcoma Versus Spindle Cell Embryonal Rhabdomyosarcoma

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Résumé

Introduction: Ovarian tumors in children are rare, with a malignant rate of 10% - 20%. Beyond common epithelial or germ cell tumors, mesenchymal tumors like spindle cell embryonal rhabdomyosarcoma (ERMS) present significant diagnostic challenges due to their histological similarity to juvenile fibrosarcoma. This study reports a case of a 7-year-old girl to highlight how morphological overlap can lead to diagnostic errors and the critical necessity of immunohistochemistry (IHC) in establishing a diagnosis. Methods: A study was performed on a 7-year-old patient who was initially diagnosed with juvenile fibrosarcoma. Following the patient’s death, a morphological review was conducted to challenge
the initial findings. The diagnostic process involved expanding the immunohistochemical panel from just CD34 and S100 to include myogenin, MyoD1, desmin, EMA, cytokeratin AE1/3, and vimentin to explore the possibility of ERMS. Results: Clinical presentation: The patient presented with abdominal pain, dysuria, and a 9 cm right ovarian mass invading the peritoneum.
Initial Findings: A diagnosis of juvenile fibrosarcoma was suggested based on morphology, and the patient received three cycles of Doxorubicin and Cisplatin. Outcome: The patient died two weeks after the third chemotherapy cycle. Morphological Review: Re-examination revealed a “cambium-like” tumor zone and rhabdoid cells with high mitotic activity, strongly suggesting spindle cell ERMS. IHC Results: Tumor cells expressed only vimentin; specific myogenic markers (myogenin/MyoD1) were unavailable locally, preventing formal confirmation despite strong suspicion of ERMS. Conclusion: Accurate classification of pediatric ovarian mesenchymal tumors requires more than just morphological vigilance; it necessitates robust immunohistochemical capacity. Strengthening diagnostic infrastructure and regional pathology networks is essential to avoid inappropriate management and improve patient outcomes in resource-limited settings.

Mots-clés

Pediatric Ovarian Tumor, Spindle Cell Embryonal Rhabdomyosarcoma, Juvenile Fibrosarcoma, Immunohistochemistry, Differential Diagnosis