Collagen-enriched serpiginous skin lesion in a cat resembling the linear form of localized scleroderma in humans

Localized scleroderma (LS) is a sclerotic skin disorder rarely reported in the veterinary literature. We herein report the first case of a linear LS-like skin lesion in a cat. A 1-year-old castrated male Himalayan cat was presented with a 1-month history of an alopecic, indurated, serpiginous, branched skin lesion on the dorsal cervical to scapular area. The cat had no history of trauma, although a topical spot-on endectocide had been applied near the lesion. Histopathological examination revealed a focal area of hyperplastic dermal collagen with the absence of pilosebaceous units. The cutaneous lesion remained unchanged during a 2-year follow-up period. Clinical and histopathological similarities of this skin lesion with those of the linear form of LS in humans were considered.