ABSTRACT:
Primary pulmonary neoplasms are uncommon in veterinary medicine; but most frequently affected are dogs. It appears that the number of primary pulmonary neoplasms is increasing in companion animals, due to the increase in life expectancy, improvement of diagnostic techniques and greater contact with air pollutants. This study was realized to identify, analyze the frequency, and to characterize pathological and immunohistochemical findings of primary pulmonary neoplasms in dogs of the metropolitan region of Porto Alegre, Rio Grande do Sul. From January 2003 to June 2016, 6,037 necropsies were performed and in 36 of them primary pulmonary neoplasm was found. The most frequent neoplasm in this study was papillary adenocarcinoma (30.5%) followed by lepidic adenocarcinoma (22.2%). The age of affected dogs ranged from 4 to 16 years, with a mean of 11 years. The frequency of male dogs (63.9%) prevailed over females (36.1%). Through immunohistochemical evaluation all epithelial neoplasms were positive for pancytokeratin, 70.6% were positive for thyroid-1 transcription factor and 23.5% had co-expression of pancytokeratin and vimentin. Two mesenchymal tumors showed immunostaining for vimentin and S-100, were negative for smooth-muscle actin and melan-A immunohistochemistry and Masson’s trichrome histochemical technique and were diagnosed as malignant peripheral nerve sheath tumors, rarely found as primary lung tumor in animals. If one has difficulty to establish a diagnosis only through routine histological examination, it is necessary to emphasize the importance of the immunohistochemical technique for the diagnosis of primary pulmonary neoplasms in dogs.
INDEX TERMS:
Immunohistochemistry; pulmonary neoplasm; dogs; Rio Grande do Sul; Brazil; diseases of dogs; lung tumors; lung; pathology
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