Stern et al., Apocrine Adenocarcinoma in the Eyelid of a Miniature Pinscher. Braz J Vet Pathol, 2011, 4(2), 142-144. Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007. 142 Case Report Apocrine Adenocarcinoma in the Eyelid of a Miniature Pinscher Adam W. Stern 1 , Lauren P. Eisele 2 1 Veterinary Diagnostic Laboratory, University of Illinois, Urbana, IL 2 Creekside Veterinary Clinic, Murphysboro, IL Corresponding Author: Adam W. Stern, DVM, CMI-IV, CFC Veterinary Diagnostic laboratory, University of Illinois, Urbana, IL, 61802 USA Submitted March 4 th 2011, Accepted May 12 th 2011 Abstract A 12-year-old spayed female miniature pinscher canid presented to the referring veterinarian with a 1 month history of a right eyelid mass. No other masses besides a previously diagnosed lipoma were identified after physical examination and thoracic radiographic examination. Histologically, neoplastic cells formed glands and were subdivided by a fibrous stroma, exhibited moderate cellular pleomorphism, and were immunoreactive for cytokeratin 7. Based on these findings an apocrine adenocarcinoma of the eyelid was diagnosed. Key Words: Apocrine adenocarcinoma, canine, eyelid, cytokeratin, CK7, CK20 Apocrine adenocarcinomas occur uncommonly in dogs with reported incidence rates of 0.6% in one study and 2.2% in another study (1, 2). A majority of apocrine gland malignances occur on the legs of dogs, although apocrine adenocarcinomas have been reported on the head, thorax, and abdomen (3, 4). The median survival time for dogs with completely excised apocrine glands adenocarcinomas that did not have invasion of vasculature by neoplastic cells is 30 months (3). The eyelid is a rarely report site of incidence for apocrine gland adenocarcinomas with only a single case report in the veterinary literature (5). In that report, a 13-year-old male Shetland Sheepdog was diagnosed with a probable adenocarcinoma of the eyelid based on HE findings and identification of intracellular PAS- positive and diastase-resistant granules. Here we describe a case of an apocrine adenocarcinoma in the eyelid of a dog and its immunohistochemical staining pattern. A 12-year-old spayed female Miniature pinscher canid presented to its former veterinarian in December 2009 with a swelling over the right eye. A mass within the right scapular region was identified and was diagnosed as a lipoma. Antibiotics of unknown type were prescribed and the swelling subsided. In October 2010, the dog presented to its current veterinarian for a mass above the right eye within the eye lid. On physical examination the mass was pressing on the globe of the right eye and the eye was difficult to visualize. The mass expanded the eyelid and could be visualized on both the anterior and posterior surface of the eyelid. Results of a CBC revealed a mild thrombocytosis (613 10 3 /uL; reference range, 170 to 400 10 3 /uL). Plasma biochemical profile revealed increased triglycerides (294 IU/L; reference range, 29 to 291 mg/dL) and an increased alkaline phosphatase (877 IU/L; reference range, 5 to 131 U/L). Thoracic radiographs were performed and no pulmonary masses were identified. Differential diagnoses for this mass included a cyst of adnexal origin, abscess, granuloma, and neoplasm. The dog underwent surgical excision of the mass and a 3 cm wide incision was made from the lateral canthus of the eye. Total exenteration of orbital contents including the eyelid was performed. The eyelid mass and eye were fixed in 10% neutral-buffered formalin and was submitted to the Veterinary Diagnostic Laboratory, University of Illinois for histologic evaluation. The biopsy sample was sectioned, paraffin embedded, and 4-5 um sections were prepared and stained with hematoxylin and eosin.