Tracheobronchial neuroendocrine carcinoma in a cat.

A tracheobronchial neuroendocrine carcinoma in a 10-year-old cat with a history of coughing, dyspnoea and anorexia is described. Endoscopic examination revealed a yellowish mass protruding into the trachea and partly obstructing the right bronchial lumen. Histological examination of biopsy samples revealed a hypercellular tumour consisting of sheets or ribbons of small hyperchromatic cells, with oval to spindle-shaped nuclei and minimal cytoplasm; nucleoli and mitotic activity were absent. The findings were confirmed on post-mortem examination. The small neoplastic cells were immunolabelled to varying degrees by antibodies against neuron-specific enolase, S-100 protein, synaptophysin and vimentin. Ultrastructural studies revealed scattered neurosecretory granules and scanty cellular junctional complexes, including desmosomes and tonofilaments, in neoplastic cells.