Xanthogranulomatous Pyelonephritis Caused by Stenotrophomonas maltophilia—The First Case Report and Brief Review

Xanthogranulomatous pyelonephritis (XGP) represents a rare and severe pathology secondary to chronic urinary obstruction and recurrent infections. Commonly, this condition leads to loss of kidney function, and frequently, surgical approach is the only optional treatment. Proteus mirabilis and Escherichia coli are the most frequent pathogens associated with XGP. The actual changes in the pathogen’s characteristics increased the risk of newly acquired infections once considered opportunistic. Stenotrophomonas malthophilia is one of those agents more related to immunocompromised patients, presenting an increased incidence and modified antibiotic resistance profile in the modern era. This case report presents a healthy female patient with an underlying renal stone pathology diagnosed with XGP related to S. maltophilia urinary infection. After a complete biological and imagistic evaluation, the case was treated as pyonephrosis. Empirical antibiotic administration and a surgical approach were considered. A total nephrectomy was performed, but the patient’s condition did not improve. The patient’s status improved when specific antibiotics were administered based on the bacterial identification and antibiotic susceptibility pattern of drained perinephric fluid. Levofloxacin and Vancomycin were considered the optimal combination in this case. The histopathological examination revealed XGP secondary to chronic renal stone. The present study describes the first case of XGP related to an aerobic Gram-negative pathogen such as S. maltophilia, once considered opportunistic, in an apparently healthy female adult.

Xanthogranulomatous pyelonephritis infected with the Providencia stuartii: a case report and literature review

Background Xanthogranulomatous pyelonephritis (XGP) is a rare and severe chronic inflammatory disease of the renal parenchyma, which is most commonly associated with super-infections by bacteria such as E. coli, Proteus mirabilis, and occasionally Pseudomonas species. Case presentation Herein, we present a rare case of a patient with XGP infected with Providencia stuartii. Initially, the patient refused nephrectomy and underwent holmium laser lithotripsy and right ureteral stenting, followed by meropenem treatment of 7 days. Relapse occurred in the third month after discharge from the hospital, due to which she underwent a radical nephrectomy. Discussion The diagnosis of XGP is confirmed by histopathology. The standard treatment for XGP is antibiotic therapy and radical nephrectomy, but partial nephrectomy may be appropriate in select cases.

Case of renal cell carcinoma with immunotherapy effect mimicking xanthogranulomatous pyelonephritis

Introduction/Objective The histologic features of renal cell carcinoma (RCC) after immunotherapy are not fully established. We report the pathologic findings of one case of clear cell RCC after treatment with pembrolizumab which is a humanized monoclonal anti-PD1 antibody. Methods/Case Report 46-year-old man completed three cycles of pembrolizumab for recurrent basal cell carcinoma. A 5.0 cm mass was incidentally found within left kidney during staging CT scan. He subsequently had left radical nephrectomy. Pathologic examination of nephrectomy specimen identified one 5.0 cm, well-circumscribed, solid mass in the upper pole, confined to the kidney with predominantly hemorrhagic, focally golden-yellow soft cut surface. The remaining parenchyma appears unremarkable. The pelvicalyceal system is not dilated. Sections of tumor show predominance of foamy histiocytes, lymphoplasmacytic infiltrate, and scattered cells having pale or eosinophilic cytoplasm, conspicuous nucleoli and low nuclear: cytoplasm ratio. Cholesterol clefts and hemosiderin deposits are noted. The immunostaining profile highlights areas suspicious for viable tumor cells by using pan-keratin, CK8/18, EMA, CA9 and CD10. Focal positivity in the same area is noted by the stains of PAX 8 and AMACR. However, with numerous histiocytes, it is difficult to determine if the tumor cells are positive for Vimentin. Moreover CD 117 is negative in the tumor cells. Results (if a Case Study enter NA) NA Conclusion Differential diagnosis includes renal cell carcinoma and xanthogranulomatous pyelonephritis. The overall findings support a clear cell RCC affected by the immunotherapy. With immunotherapy-based combinations becoming standard of care in advanced malignancies, it makes the pathological diagnosis more challenging and difficult, especially for incidental tumors.

Primary squamous cell carcinoma of renal pelvis and kidney- Sole diagnosis by histopathology

Primary Squamous cell carcinoma of the renal pelvis is rare and accounts to only 0.5- 0.8 % of malignant renal tumours having poor prognosis. Chronic irritation, inflammation and infection induce the pathogenesis of this malignancy. A 53 year old male patient, presented with left flank pain since one month. On radiological investigation, his CT revealed atrophic shrunken left kidney measuring 7.9x5.2cms showing significant parenchymal thinning and complete loss of corticomedullary differentiation. A left upper ureteric calculus is seen measuring 7.5 mm with significant left renal hydronephrosis.Clinically, it was diagnosed as Xanthogranulomatous Pyelonephritis. Grossly the radical nephrectomy specimen measures 10.5x5.5x3.5cm. External surface is irregular & bosselated. On Cut surface renal architecture is effaced by necrotic mass measuring 9.5x5.0x3.0 cm involving pelvic ureter and most of renal parenchyma.Hematoxylin and eosin stained tissue revealed characteristic feature such as keratin pearls and intracellular bridges seen, rendering the diagnosis of well-differentiated keratinising squmaous cell carcinoma seen with 40% tumour necrosis associated with Keratinizing Squamous Dysplasia. In the present case, obstructive uropathy has triggered the event of malignancy. The radiologic differential diagnosis includes primary and secondary renal neoplasms and xanthogranulomatous pyelonephritis associated with renal calculi. XGP is commonly associated with lithiasis however, rarely causes keratinizing squamous metaplasia and its manifestations closely mimic renal neoplasm, leading to misdiagnosis of malignancy.The prognosis is dismal with a 5-year survival rate of <10%. CT and MRI play a crucial role in diagnosis and staging of these tumors, though histology always remains confirmatory and diagnostic.