title: Interstitial foam cells in renal biopsies: an aid in differentiating idiopathic membranoproliferative glomerulonephritis (type I) and membranoproliferative glomerulonephritis associated with systemic lupus erythematosus.
abstract: A patient with nephrotic syndrome whose renal biopsy showed membranoproliferative glomerulonephritis (MPGN) is described. Clinical and laboratory findings included an erythematous malar flush, proteinuria, casts in the urine and a positive antinuclear factor. Hence, it was not clear whether the MPGN was idiopathic, secondary to early systemic lupus erythematosus (SLE) or mainly a renal form of SLE. Treatment with prednisone and azathioprine was unsuccessful, and no new clinical or serological features of SLE appeared. A second renal biopsy 19 months later showed MPGN and large numbers of interstitial foam cells. The finding of foam cells prompted a review of other renal biopsies which were diagnosed as MPGN type I and diffuse proliferative lupus nephritis (DPLN), including lupus-associated MPGN. Nine of thirty-eight (24%) MPGN type I but none of 22 DPLN biopsies contained interstitial foam cells. Therefore, finding foam cells in a renal biopsy may help in differentiating MPGN type I from lupus-associated MPGN.
authors.affiliation: Department of Pathology, Hospital for Sick Children, Toronto, Ont., Canada.
authors.forename: S
authors.initials: S
authors.lastname: Poucell
authors.forename: P
authors.initials: P
authors.lastname: Thorner
authors.forename: J W
authors.initials: JW
authors.lastname: Balfe
authors.forename: R
authors.initials: R
authors.lastname: Baumal
mesh_terms: D000293:Adolescent; D001706:Biopsy; D003937:Diagnosis, Differential; D005260:Female; D005487:Foam Cells / Q000473:pathology*; D015432:Glomerulonephritis, Membranoproliferative / Q000150:complications / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000175:diagnosis / Q000473:pathology*; D008264:Macrophages / Q000473:pathology*