• Basal cell tumours (BCT) are rare in horses. In one American study, it was suggested that around 1.2% of all lesions biopsied from the skin of horses were BCT (Schaffer et al. 2013).
• They can occur in any equid at any age but are found predominantly in animals over 6 years of age.
• They are invariably benign neoplasms but can be locally invasive.
• Malignant forms are extremely rare
• They normally appear as single, solitary, sometimes ill defined, firm, nodular skin mass/es. Changes can be present in the overlying epidermis such as alopecia (hair loss), hyperpigmentation or ulceration.
• Generally, they measure <5 cm in diameter but larger ones are occasionally found.
• They can be easily confused with sarcoids, squamous cell carcinoma, melanoma, trichoepithelioma, sebaceous or apocrine neoplasms or non-neoplastic follicular cysts, foreign body granuloma and pyogranuloma.
• Diagnosis is made by biopsy and histological confirmation.
• Full excision is nearly always curative.

They are most commonly found on the

• Trunk / tail
• Distal Limb – this is the most common predilection site
• Face
• Neck

There have been reports of lesions also occurring on the eyelids, nictitating membranes, pectoral area, commissure of the mouth, vulva, buttocks, prepuce and tail.

• Full surgical excision is generally curative (Slovis et al. 2001)