Giant cell variant of malignant fibrous histiocytoma in dogs: 10 cases (1986-1993).

Signalment, tumor sites, clinicopathologic, radiographic, and ultrasonographic features, as well as treatment protocols and survival information, were evaluated for 10 dogs with a histologic diagnosis of giant cell variant of malignant fibrous histiocytoma. Common clinical findings included subcutaneous masses, weight loss, anorexia, and lethargy. Laboratory abnormalities included anemia, hypoalbuminemia, and high concentrations of serum hepatic enzymes. Radiography and ultrasonography were useful in staging the extent of metastasis. Seven dogs had tumor metastasis at the time of diagnosis. Two other dogs developed evidence of metastasis during the course of treatment. The most common sites of tumor involvement were subcutaneous tissues, lymph nodes, liver, and lungs. Treatment protocols included surgical resection, intraoperative radiotherapy, and chemotherapy. Median survival time of all dogs was 61 days. Median survival time of the 6 treated dogs was 161 days. Findings on necropsy revealed metastasis with multiple organ involvement. The giant cell variant of malignant fibrous histiocytoma was determined to be a highly metastatic neoplasm in dogs, which may be responsive to surgical excision, chemotherapy, or radiotherapy.