Feline dermoid cyst: Retrospective case series and literature review

Dermoid cysts are developmental abnormalities usually located at the dorsal body midline. Histologically, these lesions reduplicate the skin, with associated collagen bundles, adnexal structures, and are filled by keratin and hairs. While these cysts have well-recognized breed and anatomical predispositions in dogs, the information in feline patients is restricted to scattered case reports and anecdotal data. Through a multi-institutional retrospective case series, we aim to describe the clinical and demographic features of this condition in cats. We retrieved a total of 220 cases. The average age at the time of diagnosis was 5.5 years, with 59.5% (131/220) being males. Domestic short hairs were the most represented breed, accounting for 56.4% (124/220) of the cases. The average cyst diameter was 1.4 cm, and 99.5% (219/220) of the cases the cysts were cutaneous and subcutaneous with the most common anatomical location being the neck (55.9%; 123/220). One dermoid cyst was in the mesentery. In most cases, no associated inflammatory lesions were reported (66.4%; 146/220). The anatomical location of the dermoid cyst did not differ significantly among sexes (Chi-square test, P = .840), breeds (Chi-square test, P = .999), ages (Chi-square test, P = .627), or other histological findings related to the cyst (Chi-square test, P = .363).