MRI appearance of primary non-Hodgkin's lymphoma of bone

Objective. To evaluate the signal characteristics of primary non-Hodgkin's lymphoma of bone on MRI. Designs and patients. Ten patients with primary non-Hodgkin's lymphoma of bone were included in the study. T1- and T2-weighted imaging was performed. The signal intensity of the lesions was compared with that of the surrounding muscle. Results. The results of the MRI were compared with the histological findings. In the majority of cases (5/10) the lesion involved the femur. In one case each the tibia, humerus, ileum, sacrum, and skull, respectively, were affected. A soft tissue mass was present in four cases. In nine of ten cases on T1-weighted imaging the lesion was hypointense. On T2-weighted imaging seven of ten lesions were hypointense compared with muscle, one isointense and, in two cases, part of the lesion showed slightly hyperintense signal. In all ten cases the signal pattern appeared inhomogeneous. Pathological examination showed extensive fibrosis in the majority of cases. Conclusion. According to our results there is decreased signal intensity of bone marrow on both T1- and T2-weighted imaging, unlike other primary round cell tumors of bone. Because the diagnoses were established with small tissue biopsies, the reason for these findings is speculative.