• Yukiho Kurosaki, Saori Itoi-Ochi, Asako Ota, Akiko Miyazaki, Hiroko Kato, Satoshi Nojima, Eiichi Morii, Kazunori Yokoi, Manabu Fujimoto, and Atsushi Tanemura.
• Department of Dermatology, Suita Municipal Hospital, Osaka, Japan.
• Medicine (Baltimore). 2023 Feb 22; 102 (8): e33128e33128.

RationaleBasal cell carcinoma (BCC) arising in the umbilicus is relatively rare, and in particular, there have been few reports mentioning peritumoral sweat gland structures histopathologically. We herein, report 2 cases of umbilical BCC with sweat gland structures within and around the tumor.Patient ConcernsA 61-year-old woman had a 2-year history of black exudative plaque in her umbilicus, and an 80-year-old woman had a 6-month history of dark brownish plaque in the umbilicus, with exudation 2 months prior to her first visit.DiagnosesBased on the histopathological finding, both cases were confirmed as BCC. The results of immunohistochemical staining showed that the tumor cells were Ber-EP4 positive. In addition, EMA-positive glandular structures were seen within and around the tumor.InterventionsCurative resection at the level of the linea alba on the bottom side was performed.OutcomesNo relapse has been observed since resection in either patient.LessonsWe herein report 2 cases of umbilical BCC with sweat glands and ducts. Although whether peri- and/or intra-tumor sweat gland structures are the source of the tumor or arise by transdifferentiation from tumor cells remains unclear, these findings may provide clues to help understand the morphopathogenesis of umbilical BCC in the future.Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.

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