A diagnostically challenging case of Lymphoplasmacytic lymphoma involving the kidney clinically mimicking benign hypertension associated chronic kidney disease

Abstract

Abstract Introduction/Objective Lymphomas involving the kidneys are under-recognized and often do not present clinically with signs and symptoms raising suspicion for a hematological malignancy. Worsening renal function may necessitate renal biopsy, but often the clinical picture may not warrant a biopsy. We herein present a case of lymphoplasmacytic lymphoma involving the kidney clinically mimicking benign renal vascular disease associated chronic kidney disease. Methods/Case Report Elderly male with past medical history of stage 3 chronic kidney disease presumed to be due to benign hypertension and undergoing treatment for the same presented to his nephrologist for routine follow up. His renal parameters were stable, but his high blood pressure seemed to be difficult to control despite maximum medical intervention. Upon the patient’s request to know exact etiology of his kidney problem, a renal biopsy was performed. Histomorphological evaluation revealed multifocal areas of renal parenchymal infiltration by atypical lymphocytic aggregates with background renal parenchyma showing moderate arteriosclerosis, mild interstitial fibrosis, tubular atrophy and no significant glomerulopathy. Further workup of the lymphoid aggregates led to the finding of a low grade CD5 negative, CD10 negative B-cell lymphoma with plasmacytic differentiation. Molecular testing for final characterization revealed a MYD88 mutation, which along with the immunomorphological findings confirmed the diagnosis of lymphoplasmacytic lymphoma (LPL). The patient was referred to hematology-oncology and was recommended to start chemotherapy due to renal involvement. Results (if a Case Study enter NA) n/a Conclusion In medical renal biopsies, lymphocytic infiltrates in areas of interstitial fibrosis are very common, and an atypical lymphocytic infiltrate can be easily overlooked. Pathologists evaluating these biopsies should have a high degree of suspicion for a hematological malignancy if they encounter atypical lymphocytic infiltrates in the renal parenchyma. Accurate diagnosis is essential, as renal lymphoma whether primary or metastatic, requires initiation of timely systemic chemotherapy.