Giant cutaneous horn associated with a dilated pore in a cat

Abstract

This report aims to describe a rare case of a giant cutaneous horn in a domestic cat and its association with a dilated pore. A 6-year-old female domestic cat was presented to a veterinary clinic with a keratinized, horn-like lesion on the right lateral cheek. The cylindrical mass measured 9.5 cm in length, 1.5 cm in width, and 1.5 cm in thickness, and appeared firm, dark brown to black, and hyperkeratotic. Histopathological examination revealed a dermal cyst lined by well-differentiated squamous epithelium with a prominent granular layer, consistent with an infundibular origin. The cystic lumen contained compact, laminated, partially pigmented keratin, with focal areas of parakeratosis. The lesion was characterized by keratinocyte hyperplasia with extensive laminated parakeratotic hyperkeratosis. These findings led to the diagnosis of a dilated pore, a proliferative variant of the feline infundibular follicular cyst, associated with a giant cutaneous horn. This rare presentation not only provides insight into the pathogenesis and potential relationship between dilated pores and cutaneous horns in cats, but also expands the current understanding of their differential diagnoses, particularly in atypical locations such as the face.