Bone marrow infiltration in hairy cell leukemia after interferon therapy detected by magnetic resonance imaging.

Magnetic resonance imaging (MRI) can detect bone marrow infiltration by neoplastic cells in many hematological malignancies. We studied 10 patients affected by hairy cell leukemia (HCL) and treated with interferon (IFN) with both MRI and bone marrow biopsy. T1-weighted MR scans of femurs and pelvis proved to be effective to score hairy cell infiltration, while less information was obtained from the study of the lumbar vertebral column. A good correlation (less than 10% difference) was noted between biopsy and MRI in over 90% of cases. MR scans showed, in general, a higher grade of infiltration. MR scan, however, can be useful for monitoring the course of HCL and the response to the treatment. Moreover, MRI evaluating a large amount of tissue, can detect a nodular type of infiltration which can be missed in biopsy specimens.