Role of the skin biopsy in the diagnosis of XXXX .

@entity9818 @entity1 @entity455 @entity1066 @entity1381 @entity4050 @entity2106
INTRODUCTION: @entity1381 ( @entity1381 ) is a prototypic @entity9818 attributable to complement dysregulation. In the absence of complement inhibition, progressive clinical deterioration occurs. The authors postulated that a biopsy of normal skin could corroborate the diagnosis of @entity1381 through the demonstration of vascular deposits of C5b-9. MATERIALS AND METHODS: Biopsies of normal skin from 22 @entity1 with and without @entity1381 were processed for routine light microscopy and immunofluorescent studies. An assessment was made for vascular C5b-9 deposition immunohistochemically and by immunofluorescence. The biopsies were obtained primarily from the forearm and/or deltoid. RESULTS: @entity1 with classic features of @entity1381 showed insidious microvascular changes including loose luminal platelet thrombi, except in 2 @entity1 in whom a striking @entity455 was apparent in biopsied digital @entity1066 . Extensive microvascular deposits of the membrane attack complex/C5b-9 were identified, excluding 1 @entity1 in whom eculizumab was initiated before biopsy. In 5 of the 7 @entity1 where follow-up was available, the @entity1 exhibited an excellent treatment response to eculizumab. @entity1 without diagnostic clinical features of @entity1381 failed to show significant vascular deposits of complement, except 2 @entity1 with @entity2106 including 1 in whom a @entity4050 mutation was identified. CONCLUSIONS: In a clinical setting where @entity1381 is an important diagnostic consideration, extensive microvascular deposition of C5b-9 supports the diagnosis of either @entity1381 or a subset of @entity2106 @entity1 with concomitant complement dysregulation; significant vascular C5b-9 deposition predicts clinical responsiveness to eculizumab.
