AP-VAS 2012 case report: a case of lupus nephritis with predominant synchronous cellular crescent formation and myeloperoxidase-antineutrophil cytoplasmic antibody seropositivity.

Several cases with an overlap of antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (GN) and lupus nephritis (LN) features have been reported in recent years. However, the clinical and the pathologic features of this condition, including mode of development, histology, and response to treatment, are not fully understood. We report a 77-year-old woman who was diagnosed with Sjögren syndrome 15 years previously. The patient presented with acute worsening of renal function and was diagnosed with new-onset systemic lupus erythematosus. A renal biopsy specimen revealed proliferative LN with synchronous cellular crescents. She was also seropositive for myeloperoxidase-ANCA. Together with the positive staining for immunoglobulins and complement factors on immunofluorescence microscopy and scant subendothelial deposits by electron microscopy, we reached a diagnosis of ANCA-associated crescentic GN overlapping with LN. Although immunosuppressive treatment with methylprednisolone pulse therapy and intravenous cyclophosphamide followed by oral predonisolone was initiated, along with intermittent hemodialysis, these treatments did not induce remission of her GN. Therefore, she continued regular intermittent hemodialysis. However, she died because of candida pneumonia 4 months after admission. Generally, the glomeruli of patients with ANCA-associated GN exhibit different stages of crescents, namely cellular, fibrocellular, or fibrous. The histologically synchronous crescents in this case indicate that ANCA-associated GN overlapping with LN can progress more rapidly than that without LN. This overlapping type of GN may be resistant to conventional immunosuppressive therapies.