Mullerian-Type Clear Cell Carcinoma in Late Metastasis of Testicular Teratoma: First Report of a Unique Association.

Mullerian-type clear cell carcinoma is an extremely rare entity in men and is believed to arise from ectopic Mullerian embryogenesis. Mullerian-type clear cell carcinoma has not been heretofore reported as a somatic malignancy associated with teratoma. In this study, we report a 45-year-old man with this association in a metastatic teratoma presenting over 20 years after his primary testicular tumor resection. Histopathologically, the Mullerian-type clear cell carcinoma had identical morphology and immunoprofile to that seen in female patients. The neoplastic cells had atypical hobnailed nuclei, clear to eosinophilic cytoplasm and showed papillary configuration, with hyaline stroma. On immunohistochemistry, the neoplastic cells were positive for keratin AE1/AE3, EMA, MOC31, and PAX8, and were negative for TTF1, p40, CD10, RCC, KIT, AFP, CD30, OCT3/4, glypican 3, SALL4, beta-hCG, WT1, and calretinin. Fluorescence in situ hybridization performed on the tumor showed isochromosome 12p. A component of teratoma was also present. We believe this to be the first report of such a unique association.