A 75-year-old man with stage IV CKD on a background of previously poorly controlled type 2 diabetes mellitus (T2DM) was reviewed in his routine renal outpatient appointment. His renal function had been slowly worsening for the past 2 years; however, on this occasion a marked increase in creatinine and proteinuria was noted despite excellent blood glucose control during the preceding 6 months, with an average glycated haemoglobin (HbA1c) of 5% ().\nApart from the T2DM complicated by neuropathy and nephropathy, his past medical history also included hypertension.\nHe was compliant with all of his medications with no significant recent medication changes and his regular medications included gliclazide, moxonidine, telmisartan/amlodipine, oral iron sulfate and vadadustat (an oral prolyl hydroxylase inhibitor).\nHe was an ex-smoker having smoked during his teenage years and he consumed less than 3 units of alcohol/week.\nThere was no family history of renal disease or haematological malignancies.\nExamination revealed moderate lymphadenopathy in the left cervical region. There was no other peripheral lymphadenopathy and no hepatosplenomegaly. The remainder of the examination was normal.\nPlans for renal replacement therapy were made, including commencement of work-up to determine suitability for renal transplantation and to investigate the lymphadenopathy. A subsequent CT of his abdomen revealed extensive lymphadenopathy. Due to progressive fluid overload and worsening biochemical parameters, he was commenced on haemodialysis.
A 50-year-old Caucasian male with a history of alcohol and injection-drug abuse, chronic HCV infection, coronary heart disease, and idiopathic renal function impairment (creatinine clearance < 60 mL/min) for preceding four months attended in the emergency department with uremic symptomatology. He was dysphonic (O2 saturation, 85%) and hypertensive (blood pressure, 185/90 mmHg) and had prominent hepatosplenomegaly with mild peripheral edema; he had no palpable lymph nodes, skin rash, or other manifestations of systemic diseases. Laboratory analyses results were as follows: metabolic acidosis (pH, 7.123; and HCO3-, 8.6 mmol/L); mild hyperkalemia (K+, 5.7 mmol/L); hyperphosphatemia (PO43-, 10 mg/dL); hypoalbuminemia (albumin, 2.8g/L); anemia (hematocrit, 21.2%; and hemoglobin, 6.8 g/dL); thrombocytopenia (platelet, 72 × 10³/μL); lactate dehydrogenase,185 U/L; and severe renal failure (serum creatinine, 9.9 mg/dL; and urea, 199 mg/dL) with signs of glomerular involvement (urine red blood cells, 40 to 60/HPF; and 24-hour urine proteins, 3.06 g).\nThe clinical and laboratory findings on admission necessitated the immediate start of hemodialysis. Subsequent ultrasound studies revealed hepatosplenomegaly, two kidneys of normal size (right kidney, 11.7 cm; and left kidney, 11.5 cm), and parenchymal thickness (right kidney, 10 mm; and left kidney, 9.9 mm). There was no clinical or radiological sign of lymph nodes involvement. Further laboratory testing by immunological assay (ANA, anti-dsDNA, ASMA, AMA, C-ANCA, P-ANCA, and C3 complement levels) had negative results except for serum proteins electrophoresis, which showed a monoclonal gammopathy of IgM. At the same time, urine immunofixation revealed the presence of albumin, IgM, and kappa light chains, type I cryoglobulinemia, and low C4 complement levels. Considering the history of the patient and after excluding and treating all other causes of renal function deterioration, our diagnostic approach pointed towards an HCV-related renal offence in the context of cryoglobulinemia. However, the rapid decline of renal function and the absence of mixed cryoglobulinemia suggested performing the renal biopsy. While the histopathological examination of the specimen was consistent with the initial suspicion, indicating MPGN (), the immunofluorescence study revealed two unusual findings: dominant monoclonal IgMκ deposits in glomerular basement membrane and infiltration of the interstitium by abundant strongly IgM-positive lymphoid cells (). The presence of CD20 cell marker was distinctive while CD5 was absent. According to these findings, a bone marrow biopsy was performed. The histopathological examination revealed plasmacytic differentiation of small B cells and the immunophenotyping results were positive for CD20 and negative for CD5. These findings were consistent with SMZL. The patient became hemodialysis dependent and received no treatment for the lymphoproliferative disease and was monitored regularly for possible transformation to a high-differentiated lymphoma.