Primary bronchial carcinoma associated with bone marrow metastasis and paraneoplastic monoclonal gammopathy in a cat

Case summary Herein we describe an unusual metastatic pattern and paraneoplastic manifestation of a bronchial carcinoma in a cat. An 8 year-old cat presented with a diminished appetite, dysphagia, weight loss, lethargy and coughing. Thoracic radiographs revealed a lung mass. Bronchial carcinoma was diagnosed on the basis of histology and was associated with a lymphoplasmocytic infiltration of the fibrovascular stroma. Biochemistry showed hyperproteinaemia. Serum protein electrophoresis showed a narrow spike in the gamma region. Bone marrow cytology revealed an infiltrate with numerous clustered epithelial cells. The cat was euthanased 2 months later because of anorexia and poor general condition.Relevance and novel information To the best of our knowledge, this is the first clinical description of primary bronchial carcinoma associated with bone marrow metastases and paraneoplastic monoclonal gammopathy in a cat.