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Mucoepidermoid carcinoma with extensive spindled morphology and melanocytic marker expression
Takashi Oide1, Kenzo Hiroshima2, Yoko Takahashi3
1Department of Pathology, Tokyo Women's Medical University Yachiyo Medical Center, Yachiyo 276-8524, Japan; Department of Diagnostic Pathology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan; Department of Pathology, Chiba University Hospital, Chiba 260-8677, Japan.
Abstract:
Mucoepidermoid carcinoma (MEC) is the most common malignant neoplasm of the salivary gland. Albeit common, histologic variants have rarely been noted in MEC. Here, we report a 49-year-old man with a sublingual gland tumor. Histologically, the tumor was composed of spindle cells arranged in interlacing fascicules or globular nests. A few bland small glands containing mucous cells were also scattered. The spindle tumor cells completely lacked immunoreactivity for cytokeratin, and exhibited immunoreactivity for vimentin, S-100, HMB-45, Melan A, and SOX10. The tumor was initially suspected to be clear cell sarcoma, malignant melanoma, or perivascular epithelioid cell tumor with a few entrapped nonneoplastic duct epitheliums. However, reverse-transcription polymerase chain reaction revealed the CRTC3-MAML2 fusion gene product diagnostic of MEC. In fact, a very minor component of the epithelial cells was reminiscent of conventional MEC, whereas major spindled tumor cells possessed markedly altered differentiation. This is the first case report of MEC with extensive spindled morphology and melanocytic marker expression.