Sox10 and DOG1 Expression in Primary Adnexal Tumors of the Skin.

Primary skin adnexal tumors can be challenging to classify and must be discerned from cutaneous adenocarcinoma metastases from various sites. We evaluated expression of Sox10 and DOG1 in normal cutaneous adnexa and in 194 primary skin adnexal tumors, and compared their performance in discriminating primary skin adnexal tumors from cutaneous metastatic adenocarcinomas with that of p40 and p63. In normal skin adnexa, we noted Sox10 expression in both the secretory and myoepithelial cells in eccrine glands, but only in myoepithelial cells in apocrine glands. DOG1 demonstrated canalicular expression in eccrine glands, and weak expression in myoepithelial cells of apocrine glands, germinative cells of sebaceous glands, and outer root sheath of follicular infundibulum. Sox10 was expressed in 100% of cylindromas and spiradenomas, and in variable frequency in other benign and malignant tumors of sweat glands. DOG1 was positive in most cylindromas (87.5%), in only 10.5% of spiradenomas, and was variably expressed in other benign and malignant tumors of sweat glands. All syringomas (n = 20) were negative for Sox10 and DOG1. One out of the 33 follicular neoplasms was positive for Sox10 and DOG1 (3%). All sebaceous neoplasms were negative for Sox10, and 28.1% of them were positive for DOG1. Sox10 was specific (91.9%) but not sensitive (28.4%) for primary skin origin, and was far less accurate (38.5%) than p63 or p40 (95.5% accuracy). Combining Sox10 with p63 or p40 showed only very minimal gain in accuracy (96%). DOG1 expression in tumors showed low sensitivity and specificity for skin adnexal origin. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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