Common errors made by pathologists in the diagnosis of bone tumors.

The pathologist must obtain X-rays before attempting to make a diagnosis in a bone tumor. Errors are made with both benign and malignant lesions associated with calluses. Infection may stimulate a malignant bone tumor radiographically and pathologically. Secondary aneurysmal bone cyst may dominate the radiographic and pathologic findings and obscure the primary diagnosis. Osteoblastomas are becoming increasingly difficult to diagnose. The question of whether such an entity can become malignant has not been resolved. Cartilagenous tumors are often difficult to diagnose and the pathologist must not only rely on histologic findings, but in particular pay attention to the radiographic pattern which is often diagnostic. Accuracy of diagnosis in Ewing's sarcoma is essential because the treatment now can result in a cure rate of almost 40%. Certain lesions such as lymphoma or osteosarcoma can mimic this tumor. To re-emphasize the problem, the pathologist must have all the clinical information before attempting a diagnosis of a bone tumor and without the pertinent X-ray, errors are almost inevitable.