Immature Teratoma With Rhabdomyosarcomatous Transformation or Overgrowth: The First Reported Case at a Cervicovaginal Site

Background Extragonadal immature teratomas are rare, accounting for 1%-2% of all germ cell tumors. Rhabdomyosarcomatous transformation arising within an immature teratoma at a cervicovaginal site has not been previously reported. The absence of standardized treatment guidelines for this entity presents significant diagnostic and therapeutic challenges. Case Presentation A teenage girl presented with three months of prolonged vaginal bleeding and six months of foul-smelling vaginal discharge. Clinical examination revealed an obliterated vaginal cavity with an irregular mass extending to the introitus. Pelvic MRI demonstrated a 72 × 69 × 56 mm aggressive neoplastic lesion arising from the vagina and involving the cervix. The mass was excised transvaginally and measured 13.5 × 9.5 × 4.5 cm. Histopathological examination revealed clusters and trabeculae of round blue cells within a neuropil-like background, alongside rhabdoid cells with well-developed cytoplasmic striations. Immunohistochemistry demonstrated positivity for desmin, synaptophysin, neurofilament, GFAP, CD56, SALL4, and WT-1 (cytoplasmic). The final diagnosis was a Grade 3 immature teratoma with rhabdomyosarcomatous transformation. The patient declined adjuvant chemoradiation and developed radiological recurrence at six months, after which she was lost to follow-up. Conclusion To the best of our knowledge, this represents the first reported case of a primary immature teratoma with rhabdomyosarcomatous transformation arising from the cervix and vagina. This case highlights the importance of thorough histopathological sampling, multidisciplinary management, and the need for awareness of this entity in the differential diagnosis of adolescent girls presenting with vaginal masses.