Fibroadnexal hamartoma in the dog: retrospective epidemiological and histopathological study of 102 cases

Abstract

ABSTRACT: Fibroadnexal hamartoma (FH), also called focal adnexal dysplasia, is the most common hamartomatous lesion in dogs. There are few retrospective studies about FH in dogs, which did not describe histopathological findings in detail. The main objective was to conduct a retrospective study and to describe the epidemiological and histopathological characteristics of a series of 102 FH cases in dogs. Descriptive statistics and Odds Ratio were used to analyze the data. The lesions were exophytic and measured on average 2.5 cm in diameter. The anatomic sites most affected were the limbs and digital region. The animals were on average 7 years of age and both sexes were equally affected. Doberman (OR: 4.15; P=0.0069) and Schnauzer (OR: 2.50; P=0.049) showed a higher risk for FH. Recurrence was not observed in any case. Four histopathological FH subtypes were identified: follicle-sebaceous (73.53%), sebaceous (16.66%), follicular (8.82%) and sebaceous-apocrine (0.98%). Diffuse and perianexial fibroplasia and inflammation were frequently seen. Chronic inflammation and mature adipocytes were seen in 71.6% and 7.8% of the cases, respectively.