Dr Sneha Amin1, Dr Daniela Potter, Dr Jeff Wong
1Department of Renal Medicine, South-Western Sydney LHD, Sydney, Australia
Biography:
Dr Sneha Amin is a third year renal advanced trainee, who is completing her training through the Central South-West Renal Network, NSW, Australia. She received her medical degree through Western Sydney University, completed her residency at Westmead Hospital and basic training in the Royal North Shore network. Her interests include chronic kidney disease, interventional nephrology and obstetric medicine.
Background:
Post-infectious glomerulonephritis (PIGN), cryoglobulinemic vasculitis and C3 glomerulopathy (C3G) are all causes of membranoproliferative injury on renal biopsy.
Case Report:
A 47year-old-male, with no prior medical conditions, presented with a vasculitic rash two weeks post-pharyngeal illness. Blood pressure was 122/60mmHg with a normal cardiovascular examination. Urine dipstick was positive for blood and protein. Serum creatinine was 144umol/L, eGFR 50ml/min/1.732, serum albumin was 21g/L and 24-hour urine protein collection was 13g/day. ASOT titre was elevated to 1113IU/ml. He had normal C3, with low C4 levels of 0.16g/L. Other autoimmune and myeloma marker were unremarkable.
Renal biopsy revealed global endocapillary proliferation, with neutrophils, few eosinophils, and strong C3 staining. Electron microscopy showed scattered finely granular subendothelial deposits, numerous subepithelial deposits and moderate foot process effacement. An initial diagnosis of PIGN was suspected.
He was treated supportively with amoxicillin, however renal function continued to deteriorate, peaking at 500umol/l. A type 1 cryoglobulin returned positive at a titre of 2%. Bone marrow biopsy (BMB) confirmed presence of a monoclonal B lymphocytosis with chronic lymphocytic leukaemia (CLL) immunophenotype. Imaging revealed no lymphadenopathy or splenomegaly. C3 nephric factor subsequently returned positive.
His diagnosis was re-evaluated to C3G with underlying CLL and associated cryoglobulinemia. Prednisolone 60mg daily with Rituximab was commenced with improvement of creatinine to 144umol/l, eGFR 50ml/min/1.73m2.
Conclusion:
The case highlights the importance of considering alternative diagnoses in the presence of conflicting clinical features. The vasculitic rash was incongruent with the initial diagnosis of PIGN, and later explained by the presence of cryoglobulinemia. Further investigations resulted in a new diagnosis of CLL on BMB, not obvious on peripheral blood, and significantly altered the course of management.