Histopathology of Ureteropelvic Junction Obstruction
Madeline J. Cancian, MD, Gyan Pareek, MD, Anthony Caldamone, MD, Liza Aguiar, MD, Hai Wang, MD, Liza Aguiar, MD, Ali Amin, MD.
Brown University, Providence, RI, USA.
BACKGROUND: Controversy continues as to whether lower pole crossing vessels in association with ureteropelvic junction obstruction are the cause or the result of the obstructive process. Our hypothesis was that if crossing vessels create ureteropelvic junction obstruction, then the histopathology of the ureteropelvic junction should differ between those with and without crossing vessels.
METHODS: Our database was queried for patients undergoing pyeloplasty (CPT 50400, 50405, 50544) between 6/1/2002 to 3/10/3016. We excluded patients with other renal anatomic abnormalities and patients undergoing surgery for upper tract tumor. One genitourinary pathologist reviewed all slides for muscle hypertrophy, fibrosis, edema and inflammation. Statistics were modeled in SAS 9.4 using logistic regression with maximum likelihood.
RESULTS: 178 patients met inclusion criteria and pathology slides were available for 136 patients. The median age was 16 years [IQR 19 yrs]. The cause of presentation was pain in 61 (45%), prenatal hydronephrosis in 55 (40%) and postnatal incidental finding in 11 (8%). Pre-surgical renal function scans were obtained in 127 (93%) patients and 30% of patients had <40% renal function for the affected kidney. 33 patients had crossing vessels in association with an ureteropelvic junction obstruction. Degree of muscle hypertrophy (p=0.89) and fibrosis (p=0.17) were not predictive of etiology. Odds of crossing vessel increased by 4.3 times (95% CI [1.8, 9.9]) when edema was present (p=.009) and by 4.4 (95% CI [1.4, 13.7]) times when inflammation was present (p=.0103).
CONCLUSIONS: In the largest pathology series to date, histopathology showed increased inflammation in the presence of a crossing vessel how.ever similar composition of muscle and fibrosis. These data suggest that UPJO has similar patterns of muscle and fibrosis regardless of etiology. However, UPJO with an associated lower pole vessel may represent a superimposed chronic process which would explain why patients with a crossing vessel present later in life.
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