J Pathol Transl Med.  2016 May;50(3):211-216. 10.4132/jptm.2016.02.01.

Aberrant Blood Vessel Formation Connecting the Glomerular Capillary Tuft and the Interstitium Is a Characteristic Feature of Focal Segmental Glomerulosclerosis-like IgA Nephropathy

• Lim BJ
• Kim MJ
• Hong SW
• Jeong HJ

• KMID: 2164598
• DOI: http://doi.org/10.4132/jptm.2016.02.01

Abstract

BACKGROUND
Segmental glomerulosclerosis without significant mesangial or endocapillary proliferation is rarely seen in IgA nephropathy (IgAN), which simulates idiopathic focal segmental glomerulosclerosis (FSGS). We recently recognized aberrant blood vessels running through the adhesion sites of sclerosed tufts and Bowman's capsule in IgAN cases with mild glomerular histologic change.
METHODS
To characterize aberrant blood vessels in relation to segmental sclerosis, we retrospectively reviewed the clinical and histologic features of 51 cases of FSGS-like IgAN and compared them with 51 age and gender-matched idiopathic FSGS cases.
RESULTS
In FSGS-like IgAN, aberrant blood vessel formation was observed in 15.7% of cases, 1.0% of the total glomeruli, and 7.3% of the segmentally sclerosed glomeruli, significantly more frequently than in the idiopathic FSGS cases (p = .009). Aberrant blood vessels occasionally accompanied mild cellular proliferation surrounding penetrating neovessels. Clinically, all FSGS-like IgAN cases had hematuria; however, nephrotic range proteinuria was significantly less frequent than idiopathic FSGS.
CONCLUSIONS
Aberrant blood vessels in IgAN are related to glomerular capillary injury and may indicate abnormal repair processes in IgAN.

Keyword

Glomerulosclerosis, focal segmental; Glomerulonephritis, IgA; Kidney glomerulus; Neovascularization

MeSH Terms

Blood Vessels*
Bowman Capsule
Capillaries*
Cell Proliferation
Glomerulonephritis, IGA*
Glomerulosclerosis, Focal Segmental
Hematuria
Immunoglobulin A*
Kidney Glomerulus
Proteinuria
Retrospective Studies
Running
Sclerosis
Immunoglobulin A

Figure

• 

  Fig. 1. Consecutive photos of two glomeruli showing extra-efferent vessel formation in focal segmental glomerulosclerosis-like IgA nephropathy. (A, B) Extra vessels connecting the segmentally sclerosed portions of glomerular tufts and the extraglomerular space through the gap of Bowman’s capsule were observed when tracing the serial sections. These vessels were not connected to afferent or efferent arterioles in the vascular pole (solid arrows, extra vessels; open arrows, vascular poles). (B) Surrounding glomerular tufts showed capillary and endothelial proliferations in some cases (arrowhead) (periodic acid-Schiff, aldehyde fuchsin orange G, and methenamine silver stain).

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