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A 13-year-old, castrated male Maine Coon cat was presented to Oklahoma State University Boren Veterinary Medical Teaching Hospital for yearly echocardiographic examination monitoring hypertrophic cardiomyopathy ( HCM) diagnosed in 2003. Physical examination revealed a heart murmur and premature beats, likely related to HCM, but was otherwise unremarkable. A biochemistry profile revealed a hyperglobulinemia (6.3 g/dL). Cytologic examination of fine-needle aspirates from liver and spleen revealed increased numbers of plasma cells and mast cells, confirmed with subsequent histologic examination. Immunohistochemistry ( IHC) for c-kit in the spleen and liver showed mast cells predominantly exhibiting type I staining pattern, with moderate numbers exhibiting type II pattern in spleen, and scattered cells exhibiting type II and III patterns in liver. Bone marrow cytology and core biopsy documented approximately 22% plasma cells. Cutaneous masses on the cat's left shoulder and right carpus were cytologically confirmed mast cell tumors. Serum protein electrophoresis with immunofixation confirmed an IgG monoclonal gammopathy. This is an example of 2 hematologic neoplasms occurring simultaneously in a cat. Concurrent pathologies may be overlooked if a single disease is diagnosed and suspected of causing all clinical signs. Both neoplasms were well differentiated, and neoplastic cells could have easily been interpreted as a reactive population had a full workup not been performed. Missing either diagnosis could result in a potentially lethal outcome. Eleven months after diagnoses, the cat was clinically doing well following a splenectomy and oral prednisolone and chlorambucil chemotherapy. Globulins decreased to 4.9 g/dL. [ABSTRACT FROM AUTHOR]

Proliferation of tissue mast cells in more than one organ is a rare disease, called generalized mastocytosis. Findings obtained in 35 cases were compared with 125 case reports in order to elucidate the course of the disease and its clinical picture. The results indicated that generalized mastocytosis has to be divided into two variants, designated systemic mastocytosis and malignant mastocytosis. Systemic mastocytosis is characterized by urticaria pigmentosa-like skin eruptions, with simultaneous infiltration of at least one visceral organ (usually bone marrow). Other frequently involved organs are spleen, liver, and lymph nodes. The age curve is biphasic, with one peak in early childhood and another in the 6th decade. The prognosis of systemic mastocytosis is generally favorable (actuarial survival 0.88 one year after diagnosis). In contrast to systemic mastocytosis, malignant mastocytosis does not show urticaria pigmentosa-like skin lesions. In this variant of generalized mastocytosis, frequently involved organs are bone marrow, spleen, liver, and lymph nodes. Common symptoms are anemia and eosinophilia. The age curve shows a peak in later life (6th and 7th decades). Malignant mastocytosis is never seen in children. The clinical course is usually rapid, and prognosis correspondingly poor (actuarial survival 0.23 one year after diagnosis). [ABSTRACT FROM AUTHOR]