Primary bone lymphoma is an uncommon malignancy that accounts for less than 5% of all primary bone tumors. The radiographic appearances of primary bone lymphoma are variable, and, because the lesion can appear near normal on plain radiographs, a second modality such as bone scintigraphy or magnetic resonance (MR) imaging should be used. Despite this variability, the presence of a solitary, permeative, metadiaphyseal lesion with a layered periosteal reaction on plain radiographs and a soft-tissue mass on MR images, especially in a patient older than 30 years, is highly suggestive of lymphoma. The case for a diagnosis of primary bone lymphoma is further strengthened if the soft-tissue mass and marrow changes are associated with surprisingly little cortical destruction. Primary bone lymphoma has a better prognosis than many other malignant bone tumors; therefore, early identification allows for appropriate treatment. MR imaging not only permits early identification but also depicts the extent of soft-tissue involvement and can be used to assess the outcome of treatment.

The detection of adrenal lesions has increased with the expanding use of cross-sectional imaging. Magnetic resonance (MR) imaging is often useful for characterizing adrenal masses. Adrenal masses can be classified into various groups on the basis of the presence of intracellular lipid, macroscopic fat, hemorrhage, and cystic changes and the vascularity and shape of the tumor. These imaging features can be used by the radiologist to suggest or confirm a diagnosis for most adrenal masses, including adenoma, hyperplasia, simple and complicated cysts, lymphangioma, myelolipoma, pheochromocytoma, hemorrhage, cortical carcinoma, neuroblastoma, lymphoma, and metastases. Adenomas and metastases are common, and a decrease in signal intensity on out-of-phase images can be used to differentiate between them. Carcinoma is a possible diagnosis if that decrease in signal intensity is heterogeneous. Benign disease is diagnosed if macroscopic fat or a homogeneous cystlike lesion is seen. Recognition of the typical MR imaging features is important because it often changes the treatment approach and may obviate surgery.

Computed tomography (CT) is an excellent imaging modality for demonstrating the size, shape, and position of the spleen, as well as for depicting intrasplenic pathologic features. However, it has limited value in the diagnosis of splenic involvement by lymphoma.

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The authors reviewed 76 magnetic resonance (MR) images of 38 patients with osteosarcoma treated with preoperative chemotherapy (intraarterial cisplatin with or without systemic chemotherapy). Histologic maps of the surgical tumor specimens in 33 cases were correlated with either late-chemotherapy or postchemotherapy MR images. There were four MR patterns--dark, mottled or speckled, homogeneous, and cystic--that corresponded to different amounts of tumor matrix, granulation tissue, hemosiderin deposits, fluid-filled cysts, and residual viable tumor. Nested foci of residual viable tumor could not be specifically identified, although tumor progression or skip metastases were accurately depicted in four patients. Other findings included (a) peritumoral edema in the soft tissues and intramedullary space that shrank with chemotherapy, (b) chemotherapy effect in the surrounding soft tissues, (c) a dark rim around the extramedullary component of the tumors corresponding to a collagenous capsule continuous with the periosteum, (d) development of metaphyseal hemorrhages and bone marrow infarcts, and (e) intramedullary vascular channels.