A Case of Clear Cell Basal Cell Carcinoma Presenting as a Pedunculated Nodule

Abstract

A 96-year-old Japanese woman presented with a seven-year history of a slowly-growing polypoid tumor in the right inguinal region. Physical examination revealed a reddish polypoid nodule, measuring 4.5 × 3.5 cm, in the right inguinal region. The tumor was resected and histological examination revealed a large, circumscribed neoplasm located in the whole dermis. Some parts of the lesion were composed of basaloid cells of variable size, often associated with mitoses. At a higher magnification, the cell aggregations showed peripheral palisading, and cleft between the stroma and basaloid cells were observed. Other parts of the cell aggregates were composed of cells with clear cytoplasm showing peripheral palisading along the well-defined basement membrane, which are comparable to the lower portion of the outer root sheath. From these findings, a diagnosis of clear cell basal cell carcinoma was made. Since polypoid basal cell carcinoma may arise in a region other than the head and face and may also lack pigmentation, we should consider basal cell carcinoma as a differential diagnosis from polypoid tumors on the trunk.