Bone lesions with soft-tissue mass: Magnetic resonance imaging diagnosis of lymphomatous involvement of the bone marrow versus multiple myeloma and bone metastases

Bone metastases from solid primary tumors, as well as multiple myeloma and secondary lymphoma may all present with bone lesions and associated soft-ti ssue masses on magnetic resonance images of the spine. Tn bone metastases a nd myeloma, the cortex of the affected bone is usually destroyed and a bulg ing contour is observed at the site of extraosseous spread. In cases of lym phomatous involvement of the bone marrow, however, we have observed that sp read to the extraosseous soft-tissues occurs without alteration of the shap e or contour of the affected bone. In order to assess whether this pattern of spread is indeed suggestive or even diagnostic of lymphoma of the bone m arrow, we reviewed spinal bone marrow MR images of 66 patients, with bone m etastases from solid primary tumors (33 patients), multiple myeloma (20 pat ients) and stage TV lymphoma with bone marrow involvement (13 patients), wh o had bone lesions and contiguous soft-tissue masses. If tumor was present on either side of the bony cortex but the contour of the affected bone was preserved, a "wrap-around" sign was diagnosed. A "wrap-around" sign was fou nd in 12 of the 13 patients with lymphoma but in none of the patients with metastases or myeloma. On MR images of the bone marrow, the demonstration of tumor spread beyond t he bony cortex without disruption of the outline of the diseased bone may f avor the diagnosis of lymphoma more than that of metastases or multiple mye loma.