PMC9889153_01
(a) Bilateral purpura of the limbs demonstrating small-vessel vasculitis. (b) Purpura of the posterior thoracic and lumbar regions.
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The rash started in his lower extremities and spread to his upper extremities and back (Figures 1(a) and 1(b)).
(a) First renal biopsy (LM): a glomerulus containing a cellular crescent (PAS, x400). (b) First renal biopsy (LM): cellular crescent without evidence of hypercellularity (arrow) (PAMS; x200). (c) First biopsy: deposition of granular to segmental immune complexes along the GBM (IF, IgG; x400).
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Two glomeruli contained cellular crescents (Figures 2(a) and 2(b)). However, typical ultra-linear deposits of IgG, as seen in anti-GBM disease, were not observed (Figure 2(c)).
(a) Second biopsy: a glomerulus with no evidence of hypercellularity (PAS; x400). (b) Second biopsy: a glomerulus with mild endocapillary proliferation (arrow) (PAS; x400). (c) Secondary biopsy: a glomerulus with endocapillary proliferation in two segments (arrows) and, GBM breaks and crescent formation between the two segments (PAMS; x400). (d) Secondary biopsy: deposition of granular immune complexes along the GBM and, to a lesser degree, within the mesangium (IF, IgG; x400). (e) Second biopsy: thin GBM, intramembranous and para-mesangial electron dense deposits (arrows), and focal effacement of foot processes (EM; scale bar = 2 mu). (f) Second biopsy: intramembranous and mesangial electron dense deposits (arrows), and effacement of foot processes (EM; scale bar = 2 mu). (g) Second biopsy: thin GBM, intramembranous and para-mesangial electron dense deposits, endothelial cell swelling and loss of fenestration (EM; scale bar = 2 mu). (h) Tubulo-reticular inclusions within the endothelial cytoplasm (EM; scale bar = 22 mu).
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The remaining glomeruli showed a spectrum of lesions: the majority of the glomeruli appeared normal, with patent capillaries and no evidence of proliferation (Figure 3(a)). Three glomeruli revealed endocapillary proliferation (Figures 3(b) and 3(c)) with the presence of rare neutrophils, and three glomeruli showed small, noncircumferential cellular crescents. By IF, this time, the pattern of immune complex deposition was clearly granular (Figure 3(d)) and observed along the GBM and within the mesangium with the following intensities: IgG/C3/C1q (+++); IgA/Kappa/Lambda (++); and IgM (+). Tubulo-reticular inclusions were also present in the endothelial cytoplasm, and foot processes were effaced in many areas (Figures 3(e)-3(g)). Multiple tubulo-reticular inclusions were present within the endothelial cytoplasm (Figure 3(h)).
Skin biopsy. Lupus band: linear immune complexes deposition along dermo-epidermal junction (IF, C1q; x400).
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