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Case Reports

Abstract

Sebaceomas are neoplasms comprised of a predominant germinative immature sebocyte component and a minority mature sebocyte component. Clinically, they often present as small yellow-to-orange papules, often on the head and neck, and have a predilection for women in the sixth-to-ninth decades of life. Multiple histologic growth patterns have been described, with the rippled-pattern variant being particulary rare. This variant is characterized by ‘cigar-shaped’ basaloid nuclei arranged in linear and parallel rows, resembling Verocay bodies of a schwannoma. This variant can be challenging to histologically differentiate from trichoblastomas, spiradenomas, and basal cell carcinomas, often creating diagnostic difficulty, especially if the mature sebocytes are rare and the diagnostician is unaware of this entity. Herein we report a case of an 85-year-old female who presented with a 0.5 cm light yellow papule on the left superior parietal scalp. Histologic examination demonstrated a relatively circumscribed basaloid proliferation with features of palisading, including a rippled-pattern within larger tumor islands. Immunohistochemical staining demonstrated positivity for adipophilin, androgen receptor (AR), p63, and CK5/6, while Ber-EP4 and CEA were negative. A diagnosis of rippled-pattern sebaceoma was rendered. It is our aim to highlight the histologic and immunophenotypic differences between rippled-pattern sebaceomas and other similar appearing neoplasms such as basal cell carcinoma, trichoblastoma, and spiradenoma. Thus, we hope to increase awareness and improve diagnostic accuracy of this unusual variant of sebaceoma.