Embryonal Rhabdomyosarcoma (Botryoid Subtype) Affecting the Buccal Mucosa.

Rhabdomyosarcoma (RMS) is a rare oral malignant soft tissue tumor whose pathological features may influence the clinical behavior, treatment and prognosis of the lesion. We report a case of a 13-year-old female patient, presenting an asymptomatic polypoid swelling in the left buccal mucosa that was approximately 2.5 cm in diameter and 3 months evolution. The presumptive diagnosis was fibrous hyperplasia and an excisional biopsy was carried out. Pathologic analysis revealed proliferation of predominantly ovoid cells, with eosinophilic cytoplasm and pleomorphic nuclei, arranged in subepithelial cambium layer. The mucosal surface presented a papillary-verrucous appearance. Immunohistochemical analysis revealed intense positivity for desmin, myogenin and Ki-67. The diagnosis was of embryonal RMS (botryoid variant). The patient was subjected to complementary chemotherapy and radiotherapy, with no evidence of recurrence or metastatic disease after 12 months follow-up. A discussion on the clinical, histopathological, immunohistochemical and therapeutic aspects of botryoid RMS will be provided.