Systemic mastocytoma associated with lymposarcoma in an aged cat.

Systemic mastocytoma was diagnosed in a 16 year old cat. Prednisone therapy was initiated but discontinued after 11 months because of development of a duodenal ulcer. Twenty months after the initial diagnosis the cat developed dyspnea, due to enlarged pharyngeal lymph nodes. Euthanasia was performed; systemic mastocytoma and lymphosarcoma were found at necropsy.