Ectomesenchymal chondromyxoid tumour of the tongue. A review of histological and immunohistochemical features.

BACKGROUND Ectomesenchymal chondromyxoid tumour (ECT) is a rare, benign neoplasm of uncertain histogenesis, which appears to exclusively involve the oral cavity, particularly the tongue. CASE REPORT We report the case of a 27-year-old woman with a 0.7 cm tumoral lesion of 3 months' duration on the dorsum of the tongue. Histologically, it comprised well-circumscribed, unencapsulated lobular proliferations of fusiform and polygonal cells, with varying degrees of cellularity, with neoplastic cells often set in a myxoid, chondroid or hyalinized background. Immunohistochemistry revealed positivity of the neoplastic cells for antibodies directed against S-100, glial fibrillary acidic protein and vimentin, plus negativity for CD-57(leu-7), epithelial membrane antigen, smooth muscle actin, desmin and cytokeratin AE1-AE3. The diagnosis was consistent with ECT. Total excision was performed and there has been no recurrence after 10 months' follow-up. CONCLUSION This is the 37th case reported in the English language literature; ECT is characterized microscopically by a biphasic myxoid and chondroid pattern. Immunohistochemical expression of S100, glial fibrillary acidic protein and vimentin, very helpful in confirming diagnosis, suggest a probable mesenchymal and neural origin of this rare entity.