Abstract. Five soft tissue tumors of varied morphology in dogs and cats were classified as malignant fibrous histiocytomas on the basis of their histologic composition. All were composed of varying mixtures of histiocytes and fibroblasts and three contained large multinucleated cells. This giant cell variant of malignant fibrous histiocytoma was seen only in cats. These tumors are comparable to those described in man as malignant fibrous histiocytoma on the basis of the malignant histiocyte and its varied morphology and function.

This technique should provide a non-invasive and cost-effective means of diagnosing mycobacterial infections.

No abstract

Osteosarcoma is a malignant neoplasm of bone that contains at least a sarcomatous stroma and tumor osteoid. It may contain various quantities of neoplastic fibrous connective tissue, cartilage, and bone as well. Histologic classifications of this tumor are based on the proportions of these components. The three most common histologic types are osteoblastic, fibroblastic and chondroblastic [l, 2,4].A rare variant described in both man and dog is the telangiectatic osteosarcoma, also called A recent review of 25 selected cases of telangiectatic osteosarcoma in man led to the conclusion that the prognosis with this variant is bleaker than with other types of osteosarcomas [3]. It has been described as inevitably fatal in the dog [5].Dog 1, an 8-year-old female German Shepherd, had right shoulder and foreleg lameness and a subcutaneous mass in the dorsum of the neck. A skeletal radiologic survey showed a normal thorax and an osteolytic lesion of the right scapula ( fig. I). Many neutrophils in the neck mass and highly undifferentiated neoplastic cells with a few multinucleated giant cells in the scapular lesion were seen in Giemsa-stained smears of needle aspirates. The preliminary diagnoses were an abscess in the neck and undifferentiated sarcoma in the scapula. A fleshy mass with a necrotic center and a portion of the scapulo-humeral joint capsule were removed surgically and the dog was placed on a regime of chemotherapeutic drugs, Adriamycin (Doxorubicin, Adria Labs, Wilmington, Del.) and DTIC (Dacarbazine, Dome Labs, West Haven, COM.).Histologic examination showed a highly vascular mass with large and small vascular spaces lined by large neoplastic cells and masses of large anaplastic malignant cells with numerous mitotic figures (fig. 2, 3). Necrosis, hemorrhage, multinucleated cells, and some fibrosis were seen. The original diagnosis was hemangiosarcoma, but this diagnosis was changed to telangiectatic osteosarcoma when osteoid ( fig. 3) was found at reexamination.The dog did not respond to chemotherapy, and was killed. At necropsy, a bloody friable 9 X 8-cm mass was found in the right scapula and the head of the humerus.Histologic examination showed the same changes as described above and confirmed the diagnosis of telangiectatic osteosarcoma. 398Brief Communication Dog 2, a 6%-year-old female Chihuahua cross, presented with a mass in the left temporal region and a missing left rear leg, amputated three years earlier because of osteomyelitis. Radiologic examination showed lysis of the zygomatic arch and the tip of the coronoid process of the mandible. A piece of sequestered bone also was present. Initial surgery showed necrotic tissue with a bony sequestrum. The lesion was considered traumatic or infectious and was treated accordingly. A biopsy taken one month later showed, on histologic examination, areas of fibrosis, hemorrhage, aggregates of undifferentiated neqplastic sarcomatous cells with high mitotic activity and some osteoid. The diagnosis was osteosarcoma with hemorrhage and fibrosis. Palliativ...