title: Cytologic features of clear cell adnexal carcinoma in 3 dogs.
abstract: BACKGROUND
  Clear cell adnexal carcinoma is a rare cutaneous adnexal neoplasm without definitive apocrine, sebaceous, or follicular differentiation. Differential diagnoses include sebaceous carcinoma, liposarcoma, and balloon cell melanoma. Immunohistochemical analysis, with positive immunoreactivity for pancytokeratin and vimentin, aids in the diagnosis. Cytologic features of clear cell adnexal carcinoma have not been described previously.
  
  
  OBJECTIVE
  The aim of this study was to describe cytologic features of canine clear cell adnexal carcinoma.
  
  
  METHODS
  Fine-needle aspirates (FNA) obtained prior to biopsy of cutaneous neoplasms with a histologic diagnosis of clear cell adnexal carcinoma confirmed by immunohistochemical analysis were reviewed retrospectively. Slides prepared from FNA had been stained with modified Wright-Giemsa or automated aqueous Romanowsky stain.
  
  
  RESULTS
  Of 20 neoplasms diagnosed as clear cell adnexal carcinoma in dogs, FNA of the mass had been performed in 3 cases. Cytologic features were similar and included high cellularity, marked cellular pleomorphism, loose arrangement of neoplastic cells, and a light blue to gray background resulting from streaming of cytoplasm from ruptured cells. Neoplastic cells were oval to polygonal to spindle-shaped with wispy cytoplasmic projections. Cytoplasmic eosinophilic stippling, globular deposits, or pink needle-shaped inclusions were noted. Criteria of malignancy included marked anisocytosis, anisokaryosis and anisonucleoleosis, multinucleation, karyomegaly, macronucleoli, and atypical mitotic figures.
  
  
  CONCLUSIONS
  Clear cell adnexal carcinoma should be included in the cytologic differential diagnosis for a canine cutaneous mass even if an epithelial origin is not readily identified owing to lack of characteristic epithelial features, such as highly cohesive cell clusters, evident cell-to-cell junctions, and distinct cytoplasmic edges.
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Martina
authors.initials: M
authors.lastname: Piviani
authors.forename: Melissa D
authors.initials: MD
authors.lastname: Sánchez
authors.forename: Reema T
authors.initials: RT
authors.lastname: Patel
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D044963:Biopsy, Fine-Needle / Q000662:veterinary; D018280:Carcinoma, Skin Appendage / Q000473:pathology / Q000662:veterinary*; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D008297:Male; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000473:pathology / Q000662:veterinary*; D014746:Vimentin / Q000378:metabolism
chemical_list: D014746:Vimentin