From Dog
Trichoepithelioma on the skin of a dog[1]

Trichoepithelioma are a rare neoplasm of canine skin, constituting about 4% of skin tumors in dogs[2].

These tumors are characterized by differentiation to all three segments of the hair follicle, but in which trichogenesis is present, incomplete or abortive. Although the majority are benign, some can metastasize to visceral organs[3].

Clinical appearance of these tumors is characteristic, with raised growths from 1 - 5 cm in diameter, often ulcerated.

Diagnosis requires histopathological sampling, often taken during excision. Histologically, these tumors show matrical differentiation with accumulation of shadow cells within the center of the epithelial islands. Staining for β-catenin is definitive using immunohistochemistry[4].

A differential diagnosis would include basal cell carcinoma and squamous cell carcinoma.

Wide-margin excision is usually curative, but in biopsies which show a high metastatic index, palliative radiation therapy may be considered.


  1. Uni of Pennsylvania
  2. Abramo F et al (1999) Survey of canine and feline follicular tumours and tumour-like lesions in central Italy. J Small Anim Pract 40(10):479-481
  3. Hoshino Y et al (2012) Palliative radiation therapy in a dog with malignant trichoepithelioma. Aust Vet J 90(6):210-213
  4. Bongiovanni L et al (2011) β-catenin in canine skin: immunohistochemical pattern of expression in normal skin and cutaneous epithelial tumours. J Comp Pathol 145(2-3):138-147