A 72-year-old male visited a nearby hospital with a large tumor in his occipital region, which had existed since 20 years. Since malignant tumor was suspected, he was referred to our department. At the initial consultation, an elastic-hard, yellow-brown, sessile tumor, measuring 8 × 7 × 5 cm and with a flat surface, was observed in the occipital region. The tumor was resected and covered with artificial dermis. Histopathologically, the lesion was composed of basal-cell-like cells with nest formation in the dermis. A rippled pattern, or the single-line arrangement of tumor cells involving the stroma, was present. In addition, some tumor clusters revealed the differentiation to sebaceous glands, and these cells were positive for cytokeratin (AE1/AE3) and epithelial membrane antigen, which is consistent with the staining of sebaceous glands. On the contrary, tumor cells were negative for epithelial antigen (Ber-EP4), and Ki67 (MIB1) index was 5% or lower. Therefore, we diagnosed the tumor as rippled-pattern sebaceoma and not as basal cell carcinoma. Although this case was quite unique in its large size, immunostaining was useful for the definite diagnosis.
All Science Journal Classification (ASJC) codes