Fig. 3.

Histopathologic changes of papillary biopsies from PNL PH1 patients. Yasue (A and C, arrows) and microcomputed tomography (μCT) images (A, bottom right inset) of papillary biopsies of both patients 6 (creatinine clearance 74 ± 6) and 7 (creatinine clearance 123 ± 16) detected varying sized intraluminal deposits in a few inner medullary collecting ducts (IMCD). All deposits are birefringent (A, top left inset) when viewed by polarizing optics. Tissue sections stained with Masson trichrome to mark sites of fibrosis a greenish-blue revealed extensive interstitial fibrosis at sites adjacent to and away from (B, arrowheads) intraluminal deposits. Extensive interstitial fibrosis is also seen the Yasue-stained sections (A and C) at (arrows) and away from sites of deposits (arrowheads). Prominent hyaluronan staining was noted in biopsies from the papillary tip from both patients 6 and 7 (D, patient 6). Two large intraluminal deposits (marked by arrows) show hyaluronan staining of the crystalline material as well as adjacent lining cells. A number of nearby IMCD segments with no intraluminal deposits also show hyaluronan staining of their apical cell surface (arrowheads). This staining pattern is in stark contrast to the lack of hyaluronan staining in the outer cortex of patients 6 and 7. Original magnification: ×75 (A); ×100 (B and D); ×200 (C).