Renal parenchymal malacoplakia: a different stage of xanthogranulomatous pyelonephritis?

Idiopathic renal replacement lipomatosis: A diagnostic and therapeutic challenge

Renal replacement lipomatosis is a rare benign renal disorder where the renal parenchyma is replaced by mature fatty tissue. It poses a diagnostic challenge to the clinicians due to an unusual presentation and clinical features. The disease usually presents in middle age with vague pain in the affected flank and variable urological symptoms. Although the condition is preceded by calculus disease or chronic inflammation, as an extremely rare occurrence, it can occur without any pre-existing condition, as in our case. Increasing awareness among the surgeons about the existence of such a condition will help the surgical fraternity to diagnose and manage such cases properly.

A 13-Month-Old With Xanthogranulomatous Pyelonephritis With Features of Renal Malakoplakia

Xanthogranulomatous pyelonephritis is an uncommon chronic inflammatory renal disorder caused by chronic infection with gram-negative bacteria leading to destruction of the renal parenchyma and replacement with foamy lipid-laden macrophages. Renal malakoplakia is another rare form of chronic inflammatory granulomatous disease in the kidney associated with infection usually occurring in adults with immunocompromised status or debilitating disease. It is hallmarked by the finding of foamy histiocytes with distinctive basophilic inclusions (Michaelis-Gutmann bodies). We present a case of a 13-month-old male with history of congenital hydronephrosis who presented with clinical and radiologic findings suggestive of xanthogranulomatous pyelonephritis. However, further pathologic studies revealed the presence of Michaelis-Gutmann bodies, which are pathognomonic for renal malakoplakia. With this case we hope to bring further evidence to support that these two conditions are not mutually exclusive but rather represent two pathologic processes on the same disease spectrum.

Megalocytic interstitial nephritis following acute pyelonephritis with Escherichia coli bacteremia: a case report

Megalocytic interstitial nephritis is a rare form of kidney disease caused by chronic inflammation. We report a case of megalocytic interstitial nephritis occurring in a 45-yrold woman who presented with oliguric acute kidney injury and acute pyelonephritis accompanied by Escherichia coli bacteremia. Her renal function was not recovered despite adequate duration of susceptible antibiotic treatment, accompanied by negative conversion of bacteremia and bacteriuria. Kidney biopsy revealed an infiltration of numerous histiocytes without Michaelis-Gutmann bodies. The patient's renal function was markedly improved after short-term treatment with high-dose steroid.

Coexistence of renal malakoplakia and myelodysplastic syndrome

Malakoplakia is a protean systemic chronic granulomatous disease that usually targets the genito-urinary system and most particularly the bladder. Only in rare occasions do the kidneys get involved. Myelodysplastic syndrome is a heterogeneous clonal haematopoietic disorder characterised by either a hyper- or hypocellular bone marrow dysmyelopoiesis and peripheral blood pancytopenia. The synchronous association of these two unrelated disorders has never been reported. We report a 62-year-old woman who initially developed vague, relapsing gastrointestinal symptoms synchronous with renal malakoplakia and myelodysplastic syndrome.

Xanthogranulomatous pyelonephritis presenting as a pseudotumour in a 5-year-old boy

Xanthogranulomatous pyelonephritis (XGPN) is a rare, severe and atypical form of chronic pyelonephritis. It is characterised by destruction of the renal parenchyma and replacement with a chronic inflammatory infiltrate and lipid-laden macrophages resulting in a non-functional kidney. The authors report a case of a 5-year-old boy presented with a history of abdominal pain, malaise, anorexia and weight loss for 2 months. Physical examination revealed a large flank mass and the child was directed to the oncology unit on suspicion of renal tumour. Based on clinical examination and imaging, the presumptive diagnosis of XGPN of the left kidney was made. A left transperitoneal nephrectomy was performed and the histology confirmed the diagnosis. Although rare, XGPN is a clinically important entity that should be considered in the differential diagnosis of an atypical-appearance renal mass in paediatric age.