Hepatic nontuberculous mycobacterial granulomas in patients with cancer mimicking metastases: an analysis of three cases

Hepatic granulomas caused by nontuberculous mycobacteria (NTM) are an uncommon, insidious, and indolent disease. Making an accurate diagnosis of a hepatic nontuberculous granuloma is challenging because of nonspecific clinical presentations and radiological appearances, especially in patients with a history of malignant tumors, as these lesions may mimic metastases and make a dilemma for decision-making in treatment. Herein, we report three cases of hepatic nontuberculous granulomas following operations for malignant tumors, including colon cancer, ovarian adenocarcinoma, and both rectal and renal carcinoma, respectively. Two patients presented with multiple hepatic lesions and the third had a solitary nodule in the liver. Computed tomography (CT) showed low attenuating nodules without early enhancement in the arterial phase but a slight peripheral enhancement in the portal venous phase after the intravenous administration of contrast agent. Magnetic resonance imaging (MRI) showed high signal intensity on T2-weighted image, rim enhancement in the venous phase and no contrast agent of Gd-EOB-DTPA uptake in the hepatobiliary phase. The biopsy was performed, and histopathological examinations revealed the chronic granulomas composed of epithelioid histiocytes, inflammatory cells, and Langhans giant cells. The results of nested polymerase chain reaction (PCR) were positive for NTM.