ALK-positive multisystemic malakoplakia: a case report

Abstract

Abstract Background: Malakoplakia is a rare inflammatory disease of the urogenital tract. There have been no reports of malakoplakia expressing anaplastic lymphoma kinase (ALK) to date. Here, we present one case of ALK-positive multisystemic malakoplakia and discuss the clinical significance. Case Presentation: A 65-year-old Chinese woman visited our hospital for treatment of right lumbar and abdominal pain of 1 month’s duration. Imaging revealed a soft tissue shadow measuring 59 × 58 × 45 mm at the middle and upper lateral margins of the right kidney. The boundary between the right posterior lobe of the liver and the hepatic curvature of the colon was not clear, and the adjacent hepatic curvature of the colon was slightly thickened. Colonoscopy revealed a 1.6-cm hummock-shaped protrusion in the middle of the ascending colon. Right nephrectomy and partial liver resection were performed. Microscopically, sheets of histiocytes with poor intercellular adhesion were seen, with Michaelis–Gutmann bodies present in both the intracellular and extracellular interstitium. CD10-, CD68-, and CD163-positive cells were present, with Michaelis–Gutmann bodies confirmed by staining with Alcian blue, periodic acid-Schiff (PAS), periodic acid-Schiff with diastase, Von Kossa, and Prussian blue. Abnormal ALK1 and ALK (D5F3) expression was observed in the cytoplasm and nucleus of cells. However, ALK gene mutation was not detected by fluorescence in situ hybridization or whole exome next-generation sequencing. The pathological diagnosis was ALK-positive multisystemic malakoplakia. The antibiotics imipenem and vancomycin were started based on the results of drug sensitivity analysis and the patient was subsequently discharged. She experienced no discomfort during 30 months of follow-up. Conclusion: This is the first reported case of ALK-positive multisystemic malakoplakia. The expression, mechanism, and clinical significance of ALK in this disease are worthy of further study.