Rippled-pattern sebaceoma on the head

Sebaceoma is a benign sebaceous tumor that is commonly seen on the face of middle aged and older women. This tumor exhibits various histological growth patterns. "Rippled-pattern" is one of the growth patterns that shows tumor cells regularly arranged in palisading pattern. A 77-year-old man noticed a nodule on the parietal scalp two years prior to his presentation. He presented to our department due to the recurrence of the lesion after surgical treatment was performed at a previous hospital. On his initial visit to our department, a 12×11 mm skin-colored nodule was present on his parietal scalp. Histologically, the resected nodule showed a proliferation of basaloid tumor cells in the dermis, while rippled patterns were seen in parts of the tumor nests. However, sebaceous gland duct structures were not evident. Immunohistochemical staining revealed that the tumor cells were negative for Ber-EP4. Almost all the nuclei in the tumor cells stained positively for p63. In the rippled-pattern areas, adipophilin and perilipin stained positively in the cytoplasm of the tumor cells. Therefore, we diagnosed this case as rippled-pattern sebaceoma. Rippled-pattern sebaceoma arises predominantly in males and most frequently on the scalp, whereas conventional sebaceoma occurs more frequently in females and on the face. We present a typical case of rippled-pattern sebaceoma and discuss its characteristics.