Presumptive primary pulmonary mast cell tumor in 2 dogs.

Two dogs were presented, each with a large solitary pulmonary mass, and cytology confirmed mast cell tumor (MCT) in each dog. One dog was euthanized following diagnosis. Thoracic computed tomography scan and exploratory thoracotomy of the second dog revealed a right pulmonary mass that would require a radical lung resection. The patient was euthanized and histopathology confirmed a poorly granulated MCT with characteristics suggestive of epitheliotropism, an uncommon finding with MCT. These represent the first reported cases of presumptive primary pulmonary MCT in dogs.