Malakoplakia of the kidney

Successful treatment of renal malakoplakia via the reduction of immunosuppression and antimicrobial therapy after kidney transplantation: a case report

Malakoplakia is a rare, granulomatous disease that usually affects immunocompromised individuals and is generally associated with poor graft and patient survival. We present a case of renal malakoplakia after kidney transplantation (KT). A 33-year-old female patient with chronic kidney disease underwent living-donor KT at Severance Hospital. The patient was administered 375 mg/m² rituximab due to high panel reactive antibodies. Immunosuppression was initiated with 1.5 mg/kg anti-thymocyte globulin and intravenous methylprednisolone and maintained with tacrolimus, oral methylprednisolone, and mycophenolate mofetil (MMF). Six months after KT, the patient was hospitalized for a urinary tract infection with an elevated serum creatinine level of 3.14 mg/dL. Renal biopsy revealed malakoplakia involving the renal parenchyma. Upon this diagnosis, the dose of tacrolimus was reduced and MMF was stopped. Fluoroquinolone was used for 16 days, and the trimethoprim/sulfamethoxazole dose was doubled for 6 days. The patient was hospitalized for 3 weeks and closely observed during outpatient visits. Follow-up ultrasonography revealed mass-like lesions of renal malakoplakia, which disappeared 5 months after diagnosis. The serum creatinine level decreased to 1.29 mg/dL 28 months after diagnosis. Our results suggest that renal malakoplakia can be successfully treated by the reduction of immunosuppression and sustained antimicrobial therapy.

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.

Autopsy Renal Pathology

We provide an overview of assessment of the kidneys at autopsy, with special considerations for pediatric versus adult kidneys. We describe the approach to gross examination, tissue allocation when needed for additional studies of potential medical renal disease, the spectrum of congenital abnormalities of the kidneys and urinary tract, and approach to cystic diseases of the kidney. We also discuss common lesions seen at autopsy, including acute tubular injury, ischemic versus toxic contributions to this injury, interstitial nephritis, and common vascular diseases. Infections commonly involve the kidney at autopsy, and the key features and differential diagnoses are also discussed.

Granulomatous nephritis consistent with malakoplakia in a cynomolgus monkey

Malakoplakia is a rare form of chronic granulomatous inflammation in mammals, and usually affects the urinary tract in humans. In this report, we present a case of granulomatous nephritis consistent with malakoplakia in a 4-year-old male cynomolgus monkey. Gross examination showed that the kidney was markedly enlarged and adhered to the surrounding organs. Histology showed that there was diffuse interstitial infiltration of histiocytes with abundant foamy eosinophilic cytoplasm resembling von Hansemann cells, PAS-positive granular cytoplasm and occasional PAS- and iron-positive intracellular small inclusion bodies. Electron microscopy showed that these histiocytes contained abundant lysosomes and phagolysosomes but no obvious Michaelis-Gutmann bodies. Based on these findings, a diagnosis of granulomatous nephritis consistent with early malakoplakia was made. This is the first report in a monkey of a renal lesion consistent with malakoplakia.

[Case of renal parenchymal malakoplakia presenting as sepsis and treated with nephrectomy]

Malakoplakia is a rare chronic inflammatory condition characterized by defective macrophage function, most of which involve the genitourinary tract, and renal parenchymal involvement is uncommon. We present a case of malakoplakia affecting renal parenchyma. A 46-year-old woman with pyrexia and jaundice was referred to our department. Abdominal enhanced CT scan revealed a left pyelonephritis with ureteral stone and bilateral renal abscesses. Despite the insertion of a left ureteral stent and administration of antibiotics, the patient showed persistent high fever and elevated CRP, and no obvious improvement in clinical and imaging data. In view of the limited effectiveness of the conservative treatment in this case, we decided to perform left nephrectomy. The diagnosis of malakoplakia was made based on the histopathological findings of von Hansemann cells and Michaelis-Guttmann bodies detected in the nephrectomy specimen. She is clinically healthy up to the present (50 months after surgery) with normal clinical indicators and CT findings.

[Renal malakoplakia: an underestimate cause of renal failure]

Malakoplakia is an inflammatory granulomatous disease induced by defective phagocytic activity of macrophage. Malakoplakia is histologically characterized by the presence of Michaelis-Gutmann bodies in macrophages. Although not uncommon in the genito-urinary tract, isolated malakoplakia of the kidney is rarely found. Its main clinical presentation associates acute renal failure and acute pyelonephritis. The clue for diagnosis of renal malakoplakia is based on renal biopsy showing Michaelis-Gutmann bodies. Establishing the diagnosis of renal malakoplakia is essential as it determines the choice of antibiotics and duration of treatment. Prognosis remains poor, leading frequently to chronic renal failure. In this paper, we report four cases of renal malakoplakia and discuss clinical presentation, biological and pathological features, treatment and prognosis of this disease.