Breed: Labrador Retriever
Age: 7 Y
Gender: Male, Neutered
2 cm soft, movable cutaneous mass from the left front leg. Owner reports patient had been favoring leg doing well otherwise.
Click here for the IDEXX Pathology Report on this case.
Haired skin: There is a well-circumscribed but unencapsulated dermal nodule comprised of a random admixture of budding epithelial islands and cystic structures of variable size. Neoplastic epithelium is composed of basaloid epithelial cells embedded in fibrous to fibromyxoid stroma of low cellularity. Nucleoli are small and mitotic activity is low. The cysts are filled with keratinized shadow cells and keratin. Lymphocytes and plasma cells are seen throughout the mass. Excision is complete.
Haired skin: Trichoepithelioma
Trichoepitheliomas are benign neoplasms that are fairly common in dogs but uncommon in cats. These proliferate toward all three segments of the hair follicle. In dogs, these tumors occur most often on the dorsal trunk and legs but may affect other parts of the body. In cats the lesions have a predilection for the tail. There is a predisposition to tumor formation in Basset Hounds, Bull mastiffs, English Springer Spaniels, Golden Retrievers, Gordon Setters, Irish Setters and Standard Poodles.
Image 1: Low magnification view of the entire tumor (as submitted).
Image 2: Higher magnification view demonstrating the budding epithelial islands and cystic structures lined by neoplastic follicular basaloid cells. Note the accumulation of keratin and shadow cells within the lumen of the cystic structures.