Rare Coexistence of Keratinizing Squamous Metaplasia with Xanthogranulomatous Pyelonephritis

The Forgotten Complication of Recurrent Nephrolithiasis: “Squamous Cell Carcinoma of the Renal Pelvis”—A Case and Review of the Literature

“…The presence of enhancing extraluminal and exophytic mass are possible suggestive features [ 5 ]. The differential diagnosis includes xanthogranulomatous pyelonephritis and renal/extrarenal neoplasms [ 11 ]. SCC of the renal pelvis is often metastatic at the time of diagnosis and is associated with a poor prognosis (one-year survival is less than 10%) [ 5 , 6 ].…”

Complicated pyelonephritis associated with chronic renal stone disease

“…DWI can be a useful tool in differentiating between XGP and renal cell carcinoma, demonstrating a more marked restricted diffusion in the central portion of the xanthogranulomatous cavities, compatible with their inflammatory content, compared to the moderate restriction of tumor's solid regions or the free diffusion of its cystic portions; moreover, ADC values of inflammatory lesions were significantly lower than those of renal cell carcinoma [33]. The CT and MRI features of focal XGP and the most common subtypes of renal cell carcinoma are summarized in Table 2. FDG-PET/CT generally cannot distinguish renal inflammation diseases from various types of tumors [34], and the role of fine-needle aspiration cytology (FNAC) is limited due to the great resemblance between the cells of XGP and those of renal carcinoma; thus, definitive diagnosis is usually made following renal biopsy or nephrectomy [35]. It is important not to forget that there are numerous reports in the literature describing simultaneously coexistence of XGP with renal carcinoma, since both these conditions are associated with long-standing, severe, chronic stones and infections (Fig.…”

“…In fact, it is postulated that chronic irritation of the renal pelvis results in squamous metaplasia, which later increases the risk of developing into cancer [36]. Since metaplasia is known to occur in association with calculi, its presence along with XGP is not surprising, even though only isolated incidence of such lesion is described in the literature, where moreover the metaplasia had already developed into squamous cell carcinoma [35]. Anyway, whether the occurrence of simultaneous metaplasia and XGP is due to the presence of the same long-standing calculus that favors both conditions at the same time or is rather due to a renal carcinoma protruding into the renal pelvis and obstructing the urinary tract, leading to a subsequent XGP, is not clear yet [37].…”

Renal Collision Tumor in Association with Xanthogranulomatous Pyelonephritis

“…[9] The immunohistochemical staining pattern of the osteosarcoma (pancytokeratin negative) makes it less likely to have arisen from sarcomatoid differentiation of the SCC, and seemingly more likely that this second malignancy arose de novo .…”