Antineutrophil cytoplasmic antibody-positive pauci-immune glomerulonephritis associated with mantle cell lymphoma

: Renal involvement in non-Hodgkin lymphoma, especially mantle cell lymphoma (MCL) is rare. A 77-year-old man presented with acute kidney injury (AKI), which rapidly progressed to dialysis dependence. Kidney biopsy revealed patchy B-cell lymphocytic aggregates in the interstitium, which were positive for cyclin D1, consistent with atypical CD5-negative MCL as confirmed by the detection of translocation t(11;14) by FISH. Crescents were noted in 3 of 26 glomeruli; while PR-3 antineutrophil cytoplasmic antibody (ANCA) positivity and negative immunofluorescence suggested an additional pauci-immune (rapidly progressive) glomerulonephritis pattern of injury. Patient received chemotherapy (cyclophosphamide, vincristine, and prednisone), which improved his renal function and allowed for discontinuation of hemodialysis. However, he died from pulmonary hemorrhage 8 months after initial presentation. This is the first reported case of a patient with coexistence of renal MCL infiltration and ANCA-positive pauci-immune glomerulonephritis.