Bronchogenic adenocarcinoma in a cat: an unusual case of metastasis to the skin

Abstract

A 6-year-old, spayed, female, domestic shorthair cat was presented for decreased activity. A nodular lesion was found in the skin extending into the subcutaneous tissue of the right abdominal flank. On lateral and ventrodorsal radiographs of the thorax, an opacity involving the entire right caudal lung lobe and pleural effusion were noted. Cytologic evaluation of cells in the thoracic fluid and in the mass revealed a population of atypical epipthelial cells with marked anisocytosis and high N:C ratios, organized in acinar-like clusters. Multinucleated cells and several mitotic figures were found. The cytologic interpretation was carcinoma. Because of the progressive severity of clinical signs, the cat was euthanized. Histologic evaluation of tissues obtained at necropsy indicated a bronchogenic adenocarcinoma in the lung, with metastasis to the skin of the right flank, but no involvement of the digits. Based on immunohistochemical stains, the neoplastic cells strongly co-expressed cytokeratin and vimentin, and were negative for S-100 and actin-specific antigen. Bronchogenic adenocarcinoma is an uncommon neoplasm in cats, and the digits are the most common sites of metastasis. This case was unusual in that the skin of the abdominal wall was the primary site of metastasis, with no involvement of the digits.

Lung

“…23 Affected cats are generally middle to old-aged and tumor development is independent of feline immunodeficiency virus or feline leukemia virus infection. 24 No predisposing causes of feline pulmonary neoplasia have been identified. 24 Most tumors encountered are malignant and of epithelial origin (98-100%), of which adenocarcinomas are the most common (85-100%).…”

“…24 No predisposing causes of feline pulmonary neoplasia have been identified. 24 Most tumors encountered are malignant and of epithelial origin (98-100%), of which adenocarcinomas are the most common (85-100%). 10,12,25 Adenocarcinomas are not easily differentiated by topographic nomenclature (bronchial versus bronchiolar versus bronchioloalveolar) due to the extent of disease at diagnosis, and some are classified as adenosquamous carcinomas if there is significant squamous differentiation.…”

“…The author suggested that it originated from an accessory embryonic lung. 24,27 Significant changes on serum biochemistry and hematology are unusual. Interestingly, respiratory signs are reported to only occur in 33-62% of cats, 10,12,25,27,28 and in some cats lameness was the only presenting complaint.…”

“…1 False positive diagnosis of neoplasia on BAL cytology has been reported only rarely in cats with inflammatory disease, but care should always be taken with interpretation in the presence of marked inflammation. 1,24 Inflammation and hemosiderosis is common in BAL samples from cats with confirmed or suspected pulmonary neoplasia (100 and 79%, respectively). 1,24 Inflammation and hemosiderosis is common in BAL samples from cats with confirmed or suspected pulmonary neoplasia (100 and 79%, respectively).…”

“…25 However, as described previously, the accuracy of radiography for the diagnosis of pleural metastasis and lymph node involvement in one study was 70% and 62%, respectively, 12 and CT is generally considered to be more sensitive than radiography for detecting pulmonary metastatic disease. 24,40 In one study describing digital metastasis, the cats presented with lameness rather than with clinical evidence of respiratory disease. 24,40 In one study describing digital metastasis, the cats presented with lameness rather than with clinical evidence of respiratory disease.…”