Recurrent UTI
Answer: D
Recurrent urinary tract infections in otherwise healthy patients should raise concern of a possible anatomic lesion. Given her stable presentation and subacute clinical course of fever, weight loss, flank pain with a hypoechoic mass around a renal stone in a non-functioning kidney, the diagnosis of xanthogranulomatous pyelonephritis (XGP) should be entertained.
XGP is an inflammatory disease caused by chronic infection, often in the setting of renal calculus (80%). Lipid-laden macrophages invade tissues, causing necrosis and hemorrhage. Other organs are occasionally involved in this process, including surrounding viscera (with resulting pyeloenteric fistulae) or skin (pyelocutaneous fistulae).
In focal disease, nephron-sparing surgery may be an option. However, due to its invasive neoplasm-like nature, surgical resection is often required.
In some cases, XPN may appear similar to renal adenocarcinoma on CT (A). However, since the differential diagnosis is still open, Urology involvement at this time is the most appropriate (D).
In the absence of cough or TB exposure, XGP caused by mycobacterium is unlikely (B). Ateriovenous malformations typically do not present as hypoechoic masses (C).
In children, growth retardation in the setting of frequent urinary tract infections may be a clue to XGP; children are more likely to present with a palpable mass.
Reference
Li L, Parwani AV. Xanthogranulomatous pyelonephritis. Arch Pathol Lab Med. 2011 May;135(5):671-4.
Recurrent urinary tract infections in otherwise healthy patients should raise concern of a possible anatomic lesion. Given her stable presentation and subacute clinical course of fever, weight loss, flank pain with a hypoechoic mass around a renal stone in a non-functioning kidney, the diagnosis of xanthogranulomatous pyelonephritis (XGP) should be entertained.
XGP is an inflammatory disease caused by chronic infection, often in the setting of renal calculus (80%). Lipid-laden macrophages invade tissues, causing necrosis and hemorrhage. Other organs are occasionally involved in this process, including surrounding viscera (with resulting pyeloenteric fistulae) or skin (pyelocutaneous fistulae).
In focal disease, nephron-sparing surgery may be an option. However, due to its invasive neoplasm-like nature, surgical resection is often required.
In some cases, XPN may appear similar to renal adenocarcinoma on CT (A). However, since the differential diagnosis is still open, Urology involvement at this time is the most appropriate (D).
In the absence of cough or TB exposure, XGP caused by mycobacterium is unlikely (B). Ateriovenous malformations typically do not present as hypoechoic masses (C).
In children, growth retardation in the setting of frequent urinary tract infections may be a clue to XGP; children are more likely to present with a palpable mass.
Reference
Li L, Parwani AV. Xanthogranulomatous pyelonephritis. Arch Pathol Lab Med. 2011 May;135(5):671-4.
