ABSTRACT
It has been observed that some patients in complete remission (CR) after 2-chlorodeoxyadenosine (2-CdA) for hairy cell leukemia (HCL) have hypocellular bone marrow biopsies despite normal peripheral blood cell counts. This discrepancy between bone marrow cellularity and peripheral blood cell counts suggests the possibility of abnormal sites of hematopoiesis. To determine sites of hematopoiesis, 11 radionuclide scans using technetium-99m (99mTc) sulfur colloid were performed in eight patients. Although no single, pattern was observed on the 99mTc sulfur colloid scans, two of the eight patients, both with virtually aplastic marrows, had multiple areas of increased uptake in the distal appendicular skeleton, suggesting abnormal sites of hematopoiesis. The same two patients had magnetic resonance imaging (MRI), which confirmed the abnormal sites of hematopoiesis.