Secretory carcinoma of the skin is a rare adnexal carcinoma, which is morphologically and immunohistochemically identical to secretory carcinoma of the breast and is associated with the presence of t (12;15) translocation, resulting in the ETV6-NTRK3 gene fusion. Nineteen cases of primary cutaneous secretory carcinoma have been previously published in the literature. In this study, we describe 6 new cases of secretory carcinoma of the skin. The study group consisted of 5 female patients and 1 male patient, ranging in age from 57 to 98 years (mean: 74.2, median: 74). Locations included the axilla (2), neck, eyelid, thigh, and nipple base, each one. Microscopically, all but 1 tumor were well circumscribed and nonencapsulated and exhibited characteristic abundant secretions within the microcystic and tubular spaces comprised by bland oval, round to cuboidal neoplastic cells. In addition, solid areas and focal pseudopapillae were seen, and, in 1 case, a focal mucinous component with small lakes of mucin containing small tumor nests or tubules of the neoplastic cells was present. The remaining neoplasm was mostly solid and papillary, with only few characteristic lumina containing secretions. Immunohistochemically, all cases expressed S-100 protein, mammaglobin, STAT5, GATA3, and NTRK. ETV6-NTRK3 gene fusion was detected in 5 cases, whereas, in the remaining tumor, a novel NFIX-PKN1 gene fusion was found.
*Sikl’s Department of Pathology, Medical Faculty in Pilsen, Charles University in Prague
†Bioptical Laboratory, Pilsen, Czech Republic
‡Institute of Pathology, Medical Faculty University of Ljubljana, Ljubljana, Slovenia
††Department of Pathology, Moscow City Oncology Hospital №62, Moscow, Russia
‡‡Department of Pathology, Caris Life Sciences, Phoenix, AZ
§Department of Pathology, Tokyo Metropolitan Cancer and Infectious Disease Center Komagome Hospital
∥Department of Pathology, Itabashi Central Clinical Laboratory, Tokyo
¶Department of Diagnostic Pathology, Shizuoka Cancer Center Hospital, Nagaizumi
#Department of Diagnostic Pathology and Cytology, Osaka International Cancer Institute, Osaka
**Department of Dermatology, Hyogo Cancer Center, Akashi
∥∥Pathology Division, Mie University Hospital, Tsu
¶¶Department of Surgical Pathology, Hokkaido University Hospital, Sapporo, Japan
§§Department of Dermatology, University Hospital Zurich, Zurich, Switzerland
Conflicts of Interest and Source of Funding: Supported in part by a Charles University project (SVV 260 391/2018). The authors have disclosed that they have no relationship with, or financial interest in, any commercial companies pertaining to this article.
Correspondence: Dmitry V. Kazakov, MD, Sikl’s Department of Pathology, Charles University Medical Faculty Hospital, Alej Svobody 80, Pilsen 304 60, Czech Republic (e-mail: firstname.lastname@example.org).