The role of DOG1 immunohistochemistry in dermatopathology.

BACKGROUND: This study was designed to evaluate the immunoexpression of DOG1, a specific marker expressed in gastrointestinal stromal tumors, in normal skin tissues and cutaneous epithelial tumors.

METHODS: DOG1 immunostaining extent, intensity and pattern were evaluated in 69 cutaneous apocrine/eccrine tumors, 11 sebaceous tumors, 46 follicular tumors, 52 keratinocytic tumors and perilesional normal tissues.

RESULTS: In normal tissues, DOG1 was expressed strongly in the intercellular canaliculi of eccrine glands, moderately in the myoepithelial cells of mammary and anogenital mammary-like glands, and weakly or not at all in the periphery of sebaceous lobules and the lower layer of epidermis and follicular infundibulum. All apocrine-type cutaneous mixed tumors showed apical-luminal positivity for DOG1, and 4/9 of these tumors included intercellular canaliculi highlighted by DOG1 immunostaining. Other sweat gland tumors, including hidrocystadenoma, spiradenoma, cylindroma and apocrine carcinoma, also expressed DOG1 focally with an apical-luminal pattern. Although slight membranous positivity for DOG1 was observed in various tumor types, hidradenoma papilliferum exhibited diffuse membranous DOG1 staining in the myoepithelial cells.

CONCLUSIONS: DOG1 is a novel marker for identifying intercellular canaliculi and is a potential immunomarker of myoepithelial cells specific to mammary glands, anogenital mammary-like glands and tumors originating therein.