Intravascular large B-cell lymphoma: masquerade as membranoproliferative glomerulonephritis

A 55-year-old female with hypertension for 3 years presented with proteinuria (1.7 g/d). Her physical examination was unremarkable except for conjunctival pallor. Laboratory test revealed anemia (hemoglobin 6.7 gm/dl), with normal leukocytes and platelets. Peripheral smear showed mild lymphocytosis without any abnormal cells. Erythrocyte sedimentation rate was 110 mm Hg/h. Urinalysis showed 3+ albumin, and no RBC or WBC. Serum creatinine was 0.8 mg/dl, and serum albumin was 3.8 gm/dl. Serum electrophoresis was normal. Serum lactate dehydrogenase was elevated, 1660 U/l (normal 160–290 U/l). Abdominal ultrasound showed 9.9 and 10.2 cm kidney size with increased echoes, and mild hepatosplenomegaly. Renal biopsy showed diffuse, global engorged capillaries with medium-large monotonous-appearing lymphoid cells possessing stippled chromatin, single to triple nucleoli, and moderate cytoplasm, with brisk mitotic activity (Figure 1). Segmental splitting of capillary basement membranes was noticed. Immunofluorescence was negative. Immunohistochemically, lymphoid cells were positive for CD20 and BcL-2 and negative for CD3/CD68 markers. Ki-67 was >80% (Figure 2). Computed tomography of the chest, abdomen, and pelvis did not reveal any lymphadenopathy or mass lesions. A diagnosis of intravascular large B-cell lymphoma was made. Bone marrow was unremarkable, without any evidence of hemophagocytosis or lymphoma infiltration. The patient was initiated on cyclophosphamide, adriamycin, vincristine, and prednisone.Figure 2Lymphoid cells positive for CD20 and BcL-2 and negative for CD3; Ki-67 was >80%. Original magnification, X40.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Intravascular large B-cell lymphoma, as the name specifies, is proliferation of clonal lymphocytes that are restricted to vascular lumina, especially small capillaries. Lymphoma cells lack CD29 (β1-integrin) and CD54 (ICAM-1), which are critical for lymphocyte transvascular migration. Intravascular large B-cell lymphoma usually affects elderly patients with poor performance status, elevated lactic dehydrogenase serum levels, anemia, and B symptoms. This form of lymphoma is rare and underdiagnosed because it is limited to the vascular system, typically involving the kidneys, central nervous system, and skin. Glomerular involvement is very uncommon.