October 2016



Signalment (JPC # 4037525-00):   Dog

HISTORY:   Dermal mass over right temporalis

HISTOPATHOLOGIC DESCRIPTION:  Haired skin (IN-33b):  Expanding and compressing the dermis and adjacent adnexal structures and elevating the overlying epidermis is an unencapsulated, well demarcated, multilobulated neoplasm composed of polygonal cells arranged in islands, cords and trabeculae on a fine fibrovascular stroma.  Neoplastic cells have distinct cell borders and a moderate amount of eosinophilic granular to fine lacy cytoplasm which often contains variably sized 12-25um clear vacuole that occasionally contains a small amount of pale, eosinophilic, fine lacy material, one to multiple round to oval to pleomorphic nuclei with coarse chromatin, and 1-4 distinct nucleoli.  Anisocytosis and anisokaryosis are moderate to marked and mitoses average 4-6 per 10 hpf.  Rare intranuclear cytoplasmic invaginations are present.  Cords and trabeculae of neoplastic cells often form wide concentric bands around foci of lytic necrosis with necrotic debris, fibrin and hemorrhage (comedo necrosis), and the stroma is moderately edematous.  Neoplastic lobules are separated by fine fibrous bands, islands of smudgy, pale sclerotic collagen, pools of eosinophilic edema fluid, which are multifocally populated by variable numbers of lympohcytes and plasma cells.  There are aggregates of hemosiderin laden macrophages, small accumulations of hematoidin pigment, and rare foci of mineralization.  There are few small intracorneal pustules. 

 MORPHOLOGIC DIAGNOSIS:  Haired skin: Canine cutaneous clear cell adnexal carcinoma, mixed breed, canine.

 SYNONYMS: Clear cell hidradenocarcinoma; follicular stem cell carcinoma; clear cell apocrine ductular carcinoma; clear cell epitrichial carcinoma  








For histologic findings:



  1. Gross TH, Ihrke PJ, Walder EJ, Affolter VK. Skin Diseases of the Dog and Cat. 2nd ed. Ames, IA: Blackwell Publishing; 2005: 680-691.
  2. Mauldin EA, Peters-Kennedy J. Integumentary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed.. Louis, MO: Saunders Elsevier; 2016: 719.
  3. Mikaelian I, Wong V. Follicular stem cell carcinoma: Histologic,immunohistochemical, ultrastructural, and clinical characterization in 30 dogs. Vet Pathol. 2003;40:433-444.
  4. Piviani M, Sanchez MD, Patel RT. Cytologic features of clear cell adnexal carcinoma in 30 dogs. Vet Clin Pathol. 2012;41(3):405-411.
  5. Sakuma A, Nishiyama S, Yasuno K, Ohmuro T, et al. A case of canine cutaneous clear cell adnexal carcinoma with prominent expression of smooth muscle actin. J Toxicol Pathol. 2010;23:265-269.
  6. Schulman FY, Lipscomb TP, Atkin TJ. Canine cutaneous clear cell adnexal carcinoma:  histopathology, immunohistochemistry and biologic behavior of 26 cases. J Vet Diagn Invest. 2005;17:403-411.
  7. Walder EJ. Comment on: Follicular stem cell carcinoma: Histologic,immunohistochemical, ultrastructural, and clinical characterization in 30 dogs.  Vet Pathol. 2005;42(1):107-108.


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