Histologic, Immunohistochemical, and Clinical Features of 27 Mammary Tumors in 18 Male Dogs

Abstract

Twenty-seven mammary tumors from 18 male (3 intact, 15 neutered) dogs were collected. The average age at diagnosis was 9.2 years (range, 2-14 years). Seven of the dogs were Cocker Spaniels. Five dogs had multiple mammary tumors. All tumors were benign. Twenty-six were simple adenomas with mixed acinar and papillary patterns. The acinar pattern was predominant in 17 cases. One adenoma was complex with a prominent myoepithelial component. The myoepithelial component of 25 of the 25 tumors was immunohistochemically positive for calponin and p63. In the cases for which relevant clinical information was available, there was no reported history of obesity, testicular tumors, or sex hormone therapy. Surgery was the only reported treatment for these tumors. Only 1 dog was reported to have developed an additional mammary tumor. None of the dogs for which case outcome was known died or was euthanatized as a result of mammary tumor. Although uncommon, mammary tumors do occur in male dogs. Although mammary tumors may be quite cellular, the presence of an intact myoepithelium, which can be demonstrated with immunohistochemistry for calponin and p63, indicates benignancy, as the clinical behavior documents.

Not Just Uterine Adenocarcinoma—Neoplastic and Non-Neoplastic Masses in Domestic Pet Rabbits (Oryctolagus cuniculus): A Review

“…Of 226 mammary lesions in which the sex was known, only 1 adenocarcinoma occurred in a male. This is similar to feline 98 and canine 9 mammary tumors but contrasts with the situation in guinea pigs, in which a high proportion of mammary neoplasms occur in males. 3 Published reports 100 and our own data indicate that the condition of disseminated collagenous hamartomas (described in more detail below) occurs nearly exclusively in males (25/28 with known sex in our study).…”

Pathological study of neoplasms surgically excised from animals attended the veterinary teaching hospital

“…Adenoma was described in many cases, recorded depended upon metaplasia and dysplasia of epithelial cells into cuboidal to columnar with the presence of nucleus near the basement membrane (13).…”

Epidemiological, clinical and pathological evaluation of overall survival in canines with mammary neoplasms

“…The low occurrence of mammary neoplasms in male dogs corroborated previous studies that reported a frequency between 0 and 2. 7% (Brodey et al, 1983;Bearss et al, 2012). Some authors reported a lack of predisposition according to race (Peleteiro, 1994;Queiroga and Lopes, 2002).…”

“…Studies in other countries indicate that between 41 and 53% of mammary tumors are described as malignant (Brodey et al, 1983;Von Euler, 2011). However, in Brazil, the frequency of malignant neoplasms varies between 68 and 90% (Oliveira et al, 2010;Toríbio et al, 2012), which is similar to the prevalence observed in this study.…”