Cyclin D1 Expression in Ectomesenchymal Chondromyxoid Tumor of the Anterior Tongue.

Ectomesenchymal chondromyxoid tumor (ECT) is a rare benign tumor of uncertain lineage, which almost exclusively affects the anterior tongue. Herein, we report 2 cases of ECT occurring in 58- and 56-year-old males on the right and on the left side of the dorsum of the anterior tongue, measuring 18 mm and 10 mm, respectively. Despite positive resection margin in one case, none of the tumors recurred during follow-up of 6 and 5 years. Microscopically, both tumors had lobular architecture with a mixture of solid, microcystic, and chondromyxoid areas. The tumor cells were polygonal or elongated and showed mild atypia in one case. Immunohistochemically, both tumors showed diffuse expression of vimentin and focal positivity of CD10 and of smooth muscle actin. Regarding neural tissue-related markers, there was nearly diffuse expression of CD56 and neuron-specific enolase and focal positivity of PGP 9.5 in both cases and variable expression of CD57, synaptophysin, glial fibrillary acidic protein, and S-100 protein. Interestingly, we observed diffuse expression of SOX10 in one case. In both tumors, diffuse strong nuclear expression of cyclin D1 was present, without CCND1/IGH translocation or CCND1 amplification. The EWSR1 gene rearrangement was not detected. To the best of our knowledge, expression of SOX10, which may support neural crest origin of this peculiar lesion, has not been reported in ECT. The significance of strong cyclin D1 expression remains to be further investigated.