Tumors of unknown origin in the bone marrow.

Tumors of unknown origin represent a common presentation of malignancy. However, tumors of unknown origin presenting as bone marrow metastases are infrequently reported. The records of 11,820 bone marrow biopsy procedures over a 15-year period at a university hospital and a veteran's hospital were reviewed, disclosing 25 cases of tumor of unknown primary site. Most of the patients were elderly and presented with bone pain or abdominal pain. Anemia, thrombocytopenia, and a leukoerythroblastic blood picture were common hematologic findings. Examination for detection of the primary site was usually unrewarding. The median survival of patients was very short (18 days) and therapy seldom altered survival.