PMC9233511_01
Original biopsy. The length of each bar represents the distance in microns. (A) shows dilated glomerular capillaries filled with mesh-like acellular material (Masson trichrome). (B) shows capillary lumina that are dilated with lipid droplets (Oil-Red-O stain). (C) shows a fingerprint-like structure composed of granules and vacuoles within a capillary lumen. There is expansion (asterisk) of the subendothelial space (electron microscopy, 5000x).
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The biopsy showed that most glomeruli were enlarged and had markedly dilated capillary lumina filled with amorphous to mesh-like material that stained pale with hematoxylin and eosin, Periodic Acid Schiff, Jones', and Masson trichrome (Figure 1A), but positive with Oil-Red-O (Figure 1B). On electron microscopy, there were large extracellular vacuolated particles that focally showed a laminated structure (Figure 1C).
Follow up biopsy. The length of each bar represents the distance in microns. (A) shows glomerular capillaries are no longer dilated or filled with acellular material (Masson trichrome). (B) confirms the absence of lipid droplets (Oil-Red-O stain). (C) shows electron micrograph of capillary lumina that no longer contain acellular material (5000x). However, rare subendothelial spaces are expanded with lipoprotein material [osmiophilic granules (protein) and vacuoles (lipid)] as depicted in the inset (C) (15000x, corresponding to the rectangle on (C)).
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Capillary lumina were no longer dilated or filled with acellular material (Figure 2A). Oil-Red-O stain was negative (Figure 2B), consistent with the resolution of LPG. On electron microscopy, no intracapillary material was seen (Figure 2C). The subendothelial expansion seen in the previous biopsy was notably decreased, with rare persistent flocculent material with a vacuolized appearance, consistent with markedly resolved LPG (Figure 2C).