Renal Malakoplakia: A Diagnostic Challenge Presenting as a Subcapsular Collection despite Clinical Recovery

Abstract

Background: Renal malakoplakia is a rare chronic granulomatous inflammatory disorder characterized by defective macrophage function. It typically occurs in immunocompromised patients with recurrent urinary tract infections. We present a case of renal malakoplakia in a diabetic patient who progressed to nephrectomy despite initial conservative management. Case presentation: A 57-year-old female patient with a medical history of insulin-dependent type 2 diabetes mellitus was admitted to the hospital with symptoms including fever, left flank pain, and dysuria. A physical examination revealed a tender left lumbar mass. Laboratory investigations revealed a leukocytosis (16,500/mm³), elevated C-reactive protein (142 mg/L), and preserved renal function. A urine culture revealed the presence of multidrug-resistant Escherichia coli (>106CFU/mL). A subsequent Computed Tomography (CT) scan revealed an enlarged left kidney with a 9 × 6 cm multiloculated subcapsular collection, causing significant parenchymal compression, along with two non-obstructive inferior pole calculi. The initial management strategy encompassed ultrasound-guided percutaneous drainage and targeted antibiotic therapy, with the latter being contingent upon bacterial sensitivities. Notwithstanding the patient’s positive clinical recovery, Technetium-99m Dimercaptosuccinic Acid ((99m)Tc-DMSA) renal scintigraphy performed four weeks after the episode revealed a non-functional left kidney, exhibiting a 15% differential function. Following a multidisciplinary discussion, a total left nephrectomy was performed. A histopathological examination revealed extensive replacement of renal parenchyma by polymorphous inflammatory infiltrate with pathognomonic Michaelis-Gutmann bodies. These bodies are spherical, basophilic, perinuclear inclusions that demonstrate strong positivity for Periodic Acid-Schiff and Perls stains. The postoperative course was complicated by self-limited lymphorrhage. At the 3-month follow-up, the patient reported complete resolution of symptoms and remains under nephrological surveillance. Conclusion: This case underscores the diagnostic challenges posed by renal malakoplakia, a condition that can present with a wide spectrum of mimics, including infectious and neoplastic processes. Early diagnosis and prolonged antibiotic therapy with agents capable of intracellular penetration may preserve renal function; however, nephrectomy remains necessary when irreversible parenchymal damage has occurred. Diabetes mellitus has been identified as a significant risk factor for malakoplakia development through impaired leukocyte function.