Coagulase-negative staphylococcus—oftentimes a virulent masquerader

The crescents were accompanied by foci of fibrinoid necrosis with endocapillary and extracapillary fibrin. Tubular atrophy and interstitial fibrosis were absent. Interstitial inflammation was present, focal and accompanied by tubular degenerative changes. There was evidence of necrotizing vasculitis. IF revealed granular, segmental to global glomerular capillary wall positivity for IgG, kappa and lambda. Weaker staining for C3 was detected. Staining for fibrinogen highlighted areas of glomerular fibrinoid necrosis. Immunofluorescence shows intense staining of the arterial wall for IgG. The final diagnosis was ‘membranous glomerulonephritis with superimposed ANCA-associated vasculitis and extracapillary proliferation’. The patient started a 6-month course of methylprednisolone (1 g i.v.) for three consecutive days at months 1, 3 and 5, followed by methylprednisolone per os alternated with cyclophosphamide per os. The patient is in partial remission. Creatinine fell to 1.6 mg/dL while proteinuria reduced to 1.2 g/24 h. Treatment ended on September 2010.