Clinicopathologic Features of Genitourinary Malakoplakia and Analytical Utility of the MetaPath Assay.

PURPOSE: To describe the clinicopathological spectrum of genitourinary malakoplakia (MPL) and to evaluate the feasibility and clinical impact of metagenomic pathogen detection (MetaPath) performed on archival formalin-fixed paraffin-embedded (FFPE) tissue.

PATIENTS AND

METHODS

Clinical imaging, histopathology, immunohistochemistry, special stains and MetaPath results were retrospectively analysed in five MPL cases diagnosed between January 2019 and August 2025.

RESULTS

The cohort comprised four men and one woman with a median age of 65.4 years. Four lesions arose in the prostate and one in the bladder. Histology showed chronic granulomatous inflammation with numerous eosinophilic histiocytes containing 5-10 µm targetoid Michaelis-Gutmann bodies. CD68 and CD163 were diffusely positive; PAS and iron stains highlighted the inclusions. MetaPath identified pathogens in 3/5 (60%) FFPE specimens (Escherichia coli in two, Pseudomonas aeruginosa in one). Antibiotic regimens were adjusted according to MetaPath results. After a median follow-up of 6 months (range 4-8) all patients remained symptom-free.

CONCLUSION

MPL is frequently misdiagnosed as malignancy. MetaPath can reliably detect pathogens in archival tissue and guide targeted antimicrobial therapy, representing a valuable adjunct to conventional culture.