Liposarcoma: a soft tissue tumor with many presentations.

Liposarcoma is an uncommon connective tissue tumor arising from lipoblast cells. The lesion is located in body soft parts and rarely arises from the bones. The tumors are variable in presentation ranging from benign well-differentiated tumors to myxoid and round cell-dedifferentiated and pleomorphic forms which can present with metastases. The lesions are most often treated by surgical resection. Chemotherapy and radiation may be added to the treatment of the more malignant variants with some success.

Schwannoma: a rare benign tumor of soft tissues.

'Schwannomas are unusual benign tumors which arise from the surface of neural elements of the body or within the brain. They do not as a rule metastasize but may cause sometimes severe local problems on the nerves, blood vessels and adjacent bone. The tumors arise from the Sheath of Schwann, a structure on the surface of a nerve. The lesions may expand and cause considerable damage to adjacent tissues. They do not arise within bone since there are no Sheaths of Schwann within the osseous tissue but may cause local damage to the bony cortex and sometimes fractures. Rarely the lesions may metastasize and cause patients' death. The treatment is usually local resection, and most often is successful although may cause damage to the adjacent nerve.

Response of physeal cartilage to low-level compression and tension in organ culture.

The clinical response of growth plate to exogenous forces is well recognized, although the organ-level mechanisms are poorly understood. Physeal cartilage from 5- to 7-day-old bovine distal radii was subjected to 245 N of tension or 245 N of compression (0.012 MPa) in organ culture over a 24-h period. Eleven specimens (six tension, five compression) were assayed for cellular proliferation with tritiated thymidine. Eighteen specimens (12 tension, six compression) were assayed for synthetic activity with radioactive sulfate. Media were assayed for prostaglandin production. Tension increased whereas compression decreased synthetic activity and prostaglandin production by physeal cartilage in explant culture over a 24-h period. There was no significant change in thymidine uptake. Physeal cartilage can respond to both tension and compression and, in the short term, appears to alter synthetic activity without changing the rate of cell proliferation. This study system allows local sampling and manipulation of the physeal organ environment and may lead to ways of approaching growth-plate pathologies in vivo.

Aneurysmal bone cyst involving the lunate.

Aneurysmal bone cysts are rare lesions which even more rarely involve the bones of the hand. We report a case of a cyst involving the lunate which was initially mistaken for interosseous ganglion. Due to delay in diagnosis, marked destruction of the lunate occurred, necessitating excision and scapho-capitate arthrodesis. Although rare, aneurysmal bone cysts should be included in the differential diagnosis and ruled out prior to embarking on a course of treatment.

Stimulation of the synthesis of collagenase activator protein in cartilage by a factor present in synovial-conditioned medium.

We have purified a low molecular weight protein from medium conditioned by calf synovium with physical and biological properties similar to the leukocyte cytokine interleukin 1 (IL-1). The factor is active in stimulating the synthesis (three- to fivefold) of collagenase activator protein (CAP) by the surface (1-2 mm) of articular cartilage while CAP synthesis in the deeper zones of articular cartilage is not affected. Recombinant mouse IL-1 and commercially available purified human IL-1 are also capable of stimulating cartilage to synthesize and secrete CAP. The synthesis of other proteins, including collagenase, appeared to be unaffected by either the synovial factors or the human and mouse IL-1.