Malakoplakia mimicking pelvic malignancy with liver metastasis and peritoneal carcinomatosis.

Malakoplakia is a rare chronic inflammatory condition characterised by defective macrophage function, most commonly affecting the genitourinary tract. Although usually localised, it may occasionally present as a mass-forming lesion mimicking malignancy. We report the case of a 46-year-old woman presenting with a pelvic mass, acute kidney injury, and hydroureteronephrosis. Imaging demonstrated a necrotic 10.3cm pelvic mass with lymphadenopathy and hepatic lesions, raising suspicion of metastatic gynaecological malignancy. Surgical exploration identified a fibrotic, thickened pelvic peritoneum with extensive histiocytic inflammation. Histopathological evaluation confirmed malakoplakia, characterised by Michaelis-Gutmann bodies and histiocytes positive for CD68. Microbiological analysis identified Escherichia coli as the infectious agent. The clinical and radiological features of malakoplakia can closely mimic malignancy, posing a significant diagnostic challenge. Histopathological examination remains crucial for definitive diagnosis, particularly in distinguishing malakoplakia from metastatic urological or gynaecological malignancies. Immunohistochemistry and special stains, such as von Kossa, assist in confirmation. This case underscores the importance of considering malakoplakia in the differential diagnosis of pelvic masses, including those with suspected metastasis. Early recognition can prevent misdiagnosis and unnecessary surgical intervention, highlighting the need for multidisciplinary management.