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Findings: Plain film of the abdomen shows symmetric, markedly enlarged kidneys. There is evidence of increased bony sclerosis and loss of height of the L1 vertebral body. Noncontrasted CT scan of the abdomen shows symmetrically enlarged kidneys with homogeneous soft tissue. There is no evidence of cysts, obstruction or perirenal inflammatory change. Small retroperitoneal lymph nodes are appreciated. MRI of the lumbar spine shows increased density within the vertebral bodies from T12-L2, consistent with radiation change. A focal lytic lesion is seen in the L1 vertebral body.
Diagnosis: Renal lymphoma, with lymphomatous involvement of L1.
Discussion: The differential diagnosis of bilateral renal enlargement includes obstruction, infection, polycystic kidney disease, metastasis and renal vein thrombosis. Renal lymphoma is also an important consideration.
Renal involvement is seen in 8% of patients with lymphoma. Because of the absence of lymphoid tissue, primary lymphoma is uncommon. However, secondary involvement is common, and usually seen in Non-Hodgkin's disease. Bilateral involvement is three times as common as unilateral disease.
Manifestations include diffuse involvement, single or multiple nodules, or renal involvement from adjacent retroperitoneal disease. Multiple nodules are the most common pattern, with 58% of patients. Solitary masses only account for 3% of patients.
Bone involvement by lymphoma is seen in 6% of patients. The most common areas of involvement include the spine, pelvis, ribs and femur. the radiographic features vary from completely lytic to osteoblastic.
References:
Levine Errol: The Kidney, In Haaga,et al. Computed Tomography and Magnetic
Resonance Imaging of the Whole Body 3rd ed. Mosby St. Louis, 1996.
Cohan RH, et al. Computed Tomography of Renal Lymphoma. J. Comput Assist.
Tomograph 14:933-938, 1990.
Spagnoli I, et al. Roentenographic aspects of non-Hodgkin's lymphomas presenting
with osseous lesions. Skeletal Radiol 8;39-41, 1982.
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