Although the cause of primary malignant bone tumors remains unknown, some researchers hypothesize that they arise in centers of rapid skeletal growth because children and young adults with these tumors seem to be much taller than average. Other theories point to heredity factors, trauma, and excessive radiotherapy as causes.

Prior exposure to carcinogens, an underlying condition such as Paget’s disease, or radiation exposure has been linked with the development of osteogenic sarcomas, chondrosarcomas, and fibrosarcomas.

Primary malignant bone tumors may originate in osseous or nonosseous tissue. (See Types of primary malignant bone tumors, page 100.) Osseous tumors arise from the bony structure itself as well as from cartilage, fibrous tissue, and bone marrow. They include osteogenic sarcoma (the most common), parosteal osteogenic sarcoma, chondrosarcoma (malignant cartilage tumor), and malignant giant cell tumor. Together, these make up 60% of all malignant bone tumors.

Nonosseous tumors arise from hematopoietic, vascular, and neural tissues. These include Ewing’s sarcoma, fibrosarcoma, and chordoma. Osteogenic and Ewing’s sarcomas are the most common bone tumors of children.

A life-threatening complication, hypercalcemia commonly occurs from excessive calcium release associated with tumor destruction of bone. When the calcium reaches a level that exceeds the renal and GI capacity to excrete it, the calcium blood level rises above normal.

The patient may complain of bone pain and describe it as a dull ache. The pain is usually localized, although it may be referred from the hip or spine. The patient may describe the pain as more intense at night and note that movement doesn’t aggravate the pain.

Inspection may reveal weakness in the affected limb; you may also note that the patient walks with a limp. In late stages, the patient may appear cachectic, with fever and impaired mobility.