title: Canine cutaneous clear cell adnexal carcinoma: histopathology, immunohistochemistry, and biologic behavior of 26 cases.
abstract: Thirty tumors including 27 distinctive cutaneous neoplasms and 3 metastatic tumors from 26 dogs were collected from diagnostic submissions to 3 laboratories. Characteristic histopathologic features included location in the subcutis or dermis (or both); lobular, nodular, and nest-like architecture; and a component of epithelioid cells with clear cytoplasm. Additional features present in most cases included follicular dermal papilla-like structures, low mitotic index, nuclear pleomorphism, necrosis, and mineralization. Cytoplasmic periodic acid Schiff-positivity, which was abolished by pretreatment with diastase, indicated the presence of glycogen in all cases. The oil red O stain did not demonstrate cytoplasmic lipid. Melanin granules, accentuated by the Fontana-Masson method, were observed infrequently. A sparsely cellular mucinous stroma and stromal cartilaginous differentiation were uncommon. By immunohistochemistry, neoplastic cells stained positively for cytokeratin (29 of 29), vimentin (28 of 28), S-100 protein (24 of 29), and melan A (8 of 12); results were negative for smooth muscle actin and calponin in all cases. Clinical follow-up information was obtained on all 26 dogs. One tumor recurred, 1 metastasized to a regional lymph node, and 1 metastasized to regional lymph nodes twice. In another case, possible pulmonary metastasis was noted radiographically. The findings are consistent with a poorly differentiated, low-grade, adnexal carcinoma of the skin. Similar canine cutaneous neoplasms have been reported as "clear-cell hidradenocarcinoma" and "follicular stem cell carcinoma." The authors propose the designation "cutaneous clear cell adnexal carcinoma."
authors.affiliation: Armed Forces Institute of Pathology, Department of Veterinary Pathology, Washington, DC 20306-6000, USA.
authors.forename: F Y
authors.initials: FY
authors.lastname: Schulman
authors.forename: T P
authors.initials: TP
authors.lastname: Lipscomb
authors.forename: T J
authors.initials: TJ
authors.lastname: Atkin
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D018280:Carcinoma, Skin Appendage / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D004283:Dog Diseases / Q000378:metabolism / Q000473:pathology*; D004285:Dogs; D005260:Female; D008297:Male; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*