Introduction

Bone marrow biopsies performed to evaluate for metastatic disease are among the most common samples received. While advances in radiologic techniques have reduced the number of such bone marrow examinations, this method is still valuable for selected patients. Determination of the tumor type is usually not difficult in patients with a known primary tumor. However, unexpected malignancies may be identified, for example during an anemia work-up (Wong et al., 1993), or bone marrow biopsy may be performed prior to a primary tumor biopsy. For example, a bone marrow biopsy may be performed as the initial procedure in a child with an abdominal mass. The ability to diagnose a tumor based on a bone marrow examination may reduce the need for further procedures or alter the approach of a second procedure. In the setting of an unknown primary, immunohistochemical studies are often essential for characterization. Even with these studies, clinical correlation is often needed to confirm the primary diagnosis. The most common non-hematologic malignancies to involve the bone marrow are prostate, breast, and lung carcinomas, neuroblastoma, Ewing sarcoma/peripheral neuroectodermal tumor (PNET), rhabdomyosarcoma, and malignant melanoma (Anner & Drewinki, 1977; Papac, 1994).

Peripheral blood and bone marrow aspirate

Peripheral blood involvement by metastatic tumor, termed carcinocythemia, is extremely uncommon and usually represents a late event with short survival (Gallivan & Lokich, 1984) (Fig. 13.1). Other, non-specific abnormalities of the blood are more common in patients with metastatic carcinoma. These usually manifest as anemia, leukoerythroblastosis, leukocytosis, and microangiopathic hemolytic anemia.