Kidney infiltration due to malignant lymphoma

A 72-year-old Caucasian man was admitted for dyspnoea and weight loss. He had hypoalbuminaemia (1.6 g/dL) and nephrotic proteinuria (18 g/day), mild renal failure, anaemia and thrombocytopaenia. Physical examination, abdomen ultrasound and computerized tomography scan showed splenomegaly (Figure 1a and b), pleural effusion, oedema in the lower extremities, laterocervical, axillary, ilo-mediastinic, abdominal lymphadenopathy and kidneys enlargement with changed parenchymal echogenicity. Axillary lymph node biopsy showed a non-necrotizing granulomatous process with epithelioid cells and rare giant cells. We performed bone marrow aspiration with diagnosis of B lymphoproliferative process. Search of amyloid in abdominal fat, immunological and virological screening, tumour markers and monoclonal paraprotein were negative. Due to worsening of renal function, the patient began haemodialysis treatment with regression of dyspnoea and significant reduction of pleural effusion and legs oedema. Renal biopsy showed a lymphoproliferative process. On pathological examination, normal kidney architecture was extensively replaced by lymphoma with a diffuse pattern (Figure 2). The neoplasm was composed predominantly of small lymphoid cells with mildly irregular nuclear contours and moderate cytoplasm. The neoplastic cells were CD201, CD5 , CD10 , CD23 and bcl-21ve (Figure 3a and b). We made a diagnosis of marginal zone lymphoma Stage IV. Following CVP chemotherapy (cyclophosphamide, vincristine, prednisone), his renal function gradually improved and it was possible to stop dialysis. The creatinine fell to 132lmol/L and the nephrotic syndrome was in remission (albumen 31 g/L). There has been a progressive increase in the incidence of lymphomas seen over recent decades. Following the improved prognosis and longer survival of lymphoma patients, it is possible to observe more frequently the solid organ involvement. Kidney involvement can be related to obstruction, treatmentinduced toxicity and, with more interest for nephrologists, to (i) direct infiltration, (ii) association with kidney malignancies (mostly renal cell carcinoma or urothelial tumours) and (iii) association with glomerular diseases (mainly minimal change disease). Primary infiltration is rarely seen [1].