LAUSR

AIM Direct kidney involvement in B-cell lymphoproliferative disease is a rare disorder with only a few studies reported in Caucasian patients. The clinicopathological characteristics and outcome of this entity remain poorly described. METHODS We retrospectively studied all adult Chinese patients who had histology-proven renal parenchymal infiltration by malignant B-cells between 1/1/2000 and 31/12/2018 at 2 tertiary hospitals in Hong Kong. Clinical, pathological and radiological data were collected from 20 patients. Follow-up data were analyzed until 31/12/2019. RESULTS Median follow-up duration was 22 (1-171) months. Only 7 patients (35%) had established diagnosis of hematological cancer before kidney biopsy. Diffuse large B-cell lymphoma (DLBCL) was the most common subtype in our cohort (n=5, 25%). Others included low-grade B-cell lymphoma (n=11), intravascular large B-cell lymphoma (n=1), mantle cell lymphoma (n=1) and multiple myeloma (n=2). Fourteen patients (70%) presented with AKI while 12 patients (60%) had proteinuria. Seven patients (35%) had unilateral renal mass, 1 had bilateral renal masses and 1 had bilateral diffuse nephromegaly in computed tomography. Lymphomatous tubulointerstitial infiltration was the prevalent histological finding. Nine patients (45%) had coexisting renal lesions other than direct tumor infiltration. All but 1 patient received chemotherapy. Ten patients died and renal responders had a significantly better survival than non-renal responders (P=0.03). CONCLUSION Direct tumor infiltration can occur in a wide variety of B-cell lymphoproliferative disorders. Coexisting immunoglobulin-related nephropathy is frequently found. Renal biopsy is required for early diagnosis which allows timely and appropriate treatment. This article is protected by copyright. All rights reserved.