Abstract A 10–year-old crossbred neutered dog was submitted to Clinica Veterinaria de Antioquia (Medellin, Colombia) presenting a firm and circular mass of 5 cm in diameter in the lateral region of the foreskin. After histopathological evaluation, the mass corresponded to a Langerhans cell histiocytoma. The patient underwent surgical resection of the mass and was then treated with cephalexin (25 mg/kg every 12 hours, orally, for 1 week), prednisolone (20 days), disinfection of the area (every 12 hours using chlorhexidine), and applying dimethyl sulfoxide on the area (every 12 hours for 3 weeks). We consider this report has a scientific value because this type of histiocytoma is rarely described in dermatology