Feline cystadenomatosis affecting the ears and skin of 57 cats (2011-2019)

Objectives This study aimed to understand epidemiological factors associated with feline cystadenomatosis, including signalment and papillomavirus PCR status. Cystadenomatosis is an uncommon condition primarily involving the ceruminous and apocrine skin and ear glands. Methods This was a retrospective case series. Clinical records from 2011 to 2019 from a tertiary referral hospital in Boston, MA, USA were screened for cases, and case data were re-evaluated and analyzed. The total patient pool contained 65,385 individual cats, of which 797 were referred to the dermatology service. Medical records and biopsy specimens were reviewed; the information collected included signalment, clinical signs, physical examination and diagnostic tests, comorbidities and histopathologic findings. PCR was performed on biopsy specimens to test for papillomavirus DNA. Results The cystadenomatosis population consisted of 57 cases (7.1% of total cases referred to the dermatology service) with 105 affected ears. Twenty-seven cases (48 ears) were confirmed via histopathology; four cats (7%) exhibited clinically cystic lesions on the periocular, periorbital and perianal regions; only one cat did not have pinnal lesions. Domestic shorthair cats were most often affected. Relative risk for cystadenomatosis was 2.24 times higher in male cats. In 48 cats (84.2%), ears were bilaterally affected. Seven cats (12.3%) had malignant neoplasia, which included: inflamed adenocarcinoma (n = 5); mast cell tumor (n = 1); or squamous cell carcinoma (n = 1). PCR testing on biopsy specimens from 24 cats revealed feline papillomavirus type 2 DNA in only four cats. Conclusions and relevance Cystadenomatosis was more prevalent in senior non-purebred cats, over-represented in male cats and did not appear to be associated with papillomavirus, feline infectious peritonitis, feline immunodeficiency virus/feline leukemia virus status or other identifiable illnesses. Further studies are needed to investigate the causes of cystadenomatosis.