Xanthogranulomatous Pyelonephritis in the Tropics.

Xanthogranulomatous pyelonephritis (XGP) is a rare inflammatory disease caused by chronic urinary tract obstruction or suppuration that occurs in the renal parenchyma. It results in an enlarged, nonfunctioning kidney with diffuse parenchymal damage due to obstructive renal calculi and granulomatous inflammation. Differentiating XGP from renal cell carcinoma, renal tuberculosis, and pyonephrosis can be challenging both clinically and radiologically; therefore, histological investigation after nephrectomy is typically used to confirm the diagnosis. We aimed to study the clinicopathological features of XGP cases confirmed by histopathological examination following surgery. This was a retrospective analysis conducted on 55 nephrectomy specimens diagnosed as XGP over a period of 6.25 years. Clinical details, laboratory and radiological findings were retrieved from the Hospital Information System. The gross and microscopic findings were reviewed. The study included 55 cases, ranging from 6 to 73 years (mean 38 ±18.3 years). The right kidney was involved in 45.5% of patients, and the left was affected in 54.5%. The most common presenting complaint was lumbar/flank pain, followed by recurrent urinary tract infection, fever, hydronephrosis, and an abdominal mass. Surgical interventions included simple nephrectomy (n=48), nephroureterectomy (n=4), radical nephrectomy (n=2), and partial nephrectomy (n=1). Renal/ureteric stones were identified in 49 cases. After histopathological analysis, 40 patients were diagnosed with pure XGPN, 7 with associated chronic pyelonephritis, 3 with hydronephrosis, 2 with pyonephrosis, 1 with nephrocutaneous fistula, 1 with high-grade urothelial carcinoma and 1 with serositis. A positive urine culture was noted in 13 cases. Histologically, all cases revealed sheets of foamy histiocytes, along with a few multinucleated giant cells and chronic inflammation. Cases with associated chronic pyelonephritis were characterised by periglomerular fibrosis, tubular atrophy, thyroidization, and interstitial fibrosis. XGP remains an important mimicker of renal malignancy, both clinically and radiologically. Accurate histopathological diagnosis is crucial to avoid overtreatment and ensure appropriate management. Increased awareness of its clinicopathological spectrum can aid in better diagnostic accuracy and reduce unnecessary radical surgeries.