Clear cell adnexal carcinoma

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Clear cell adnexal carcinoma in the skin of the basal region of the left auricle of a dog[1]

Clear cell adnexal carcinoma (clear cell hidradenocarcinoma, follicular stem cell carcinoma) are a relatively rare malignant neoplasm of canine connective tissue.

Clear cell are characterized by divergent differentiation into cutaneous adnexa, such as apocrine sweat glands and hair follicles[2]. They presumably originate from follicular stem cells, as some tumor are immunohistochemically positive for cytokeratin and vimentin[3].

Older dogs appear predisposed and this tumor is often located in the skin or subcutis of the head and trunk[4].

Histological appearance of clear cell adnexal tumors include 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.

Criteria of malignancy include marked anisocytosis, anisokaryosis, karyomegaly, macronucleoli, and atypical mitotic figures[3].

A differential diagnosis would include mast cell tumor, balloon cell melanoma, basal carcinoma and sebaceous carcinoma.

Treatment is by wide-margin surgical excision, but recurrence is relatively common[3].

References

  1. Yasuno K et al (2009) Cutaneous clear cell adnexal carcinoma in a dog: special reference to cytokeratin expression. J Vet Med Sci 71(11):1513-1517
  2. Schulman, FY et al (2005) Canine cutaneous clear cell adnexal carcinoma: histopathology, immunohistochemistry, and biologic behavior of 26 cases. J Vet Diagn Invest 17:403–411
  3. 3.0 3.1 3.2 Piviani M et al (2012) Cytologic features of clear cell adnexal carcinoma in 3 dogs. Vet Clin Pathol 41(3):405-411
  4. Schulman FY et al (2005) Canine cutaneous clear cell adnexal carcinoma: histopathology, immunohistochemistry, and biologic behavior of 26 cases. J Vet Diagn Invest 17(5):403-411