Focal lesions on magnetic resonance imaging in aplastic anaemia: multiple metastases or haemopoietic marrow.

We describe the imaging findings in the spine of a 26-year-old man with aplastic anaemia who is undergoing immunosuppressive therapy. Magnetic resonance imaging of the thoracolumbar spine revealed multiple focal low signal intensity lesions involving most of the thoracic and lumbar vertebral bodies. A CT-guided biopsy of one of these lesions was performed at the level of L2, demonstrating normal haemopoietic tissue, with no evidence of lymphoma or metastases. Magnetic resonance imaging of bone marrow has been widely described previously, but few reports have examined the pattern of marrow regeneration following immunosuppressive therapy. The presence of low signal intensity lesions scattered through high signal intensity fatty marrow usually raises suspicion of pathology such as lymphoma, metastases or myeloma. In this case, the low signal intensity lesions represent regenerating, expanding haemopoietic marrow.