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Trichoepitheliomas and Pilomatricomas in Dogs

Hair follicle tumors are generally benign tumors that originate in the hair follicles in the skin. There are two types of hair follicle tumors, trichoepitheliomas, which arise from cystic hair follicles (follicles that have closed over, like a sac), and pilomatricomas, which arise from the cells that produce the hair follicles.

Trichoepitheliomas are small benign tumors, often found along a cat's back, shoulders, flank, tail or limbs. Pilomatricomas are rare skin tumors that develop from the hair matrix, where the cells which grow the hair follicles develop and are contained. Pilomatricomas are small and are often found on the trunk of middle-aged dogs.

Hair follicle tumors should be immediately evaluated by a veterinarian. The prognosis for these hair follicle tumors is generally positive, as the majority of the tumors are found to be benign.

Breeds that have been shown to be predisposed to hair follicle tumors are Golden Retrievers, Basset Hounds, German Shepherds, Cocker Spaniels, Irish Setters, English Springer Spaniels, Miniature Schnauzers and Standard Poodles. The prognosis for these hair follicle tumors is generally positive, as the majority of the tumors are found to be benign.

Symptoms and Types

Trichoepitheliomas

• Back
• Shoulders
• Flank
• Tail
• Limbs

Pilomatricomas

• Trunk/torso of the body

Causes

• Unknown
• Suspected genetic link

Diagnosis

Your veterinarian will perform a thorough physical exam on your dog, taking into account the background history of symptoms and medical health history that you provide.

Your veterinarian will conduct a complete physical exam on your dog, including a blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis.

Samples of the tumor will need to be taken for a close examination of the structure of the tumor. Samples will be taken for histopathologic laboratory analysis, both by fine needle aspirate (fluid sample) and by tissue biopsy. Such an analysis will determine exactly which type of hair follicle tumor is present and whether it is benign or malignant. Although this type of tumor is often found to be benign, it is possible that histopathological results will show it to be a different kind of tumor, in which case the treatment may need to be more aggressive.