Ultrasound-Guided Coarse Needle Biopsy Diagnosed Isolated Hepatic Malignant Melanoma with Undetermined Origin in TB Patient: A Case Report

Isolated hepatic malignant melanoma with undetermined origin is relatively rare and the imaging findings vary significantly in published studies. In this report, we described an elderly male patient with pulmonary tuberculosis who was diagnosed with isolated hepatic malignant melanoma with undetermined origin by ultrasound-guided percutaneous coarse needle biopsy (US-CNB). The hepatic melanoma was detected accidentally on chest CT. On contrast-enhanced ultrasound (CEUS), it presented an enhancement pattern of fast washin and slow washout. However, on magnetic resonance imaging (CEMRI), it showed non-rim hyperenhancement in the arterial phase but hypointensity in the late phase, mimicking hepatocellular carcinoma. With inconsistent results, the patient underwent fluorine-18-fluro-2-deoxy-D-glucose-positron emission tomography/computed tomography (18F-FDG-PET/CT). The mass showed mild 18F-FDG uptake with SUVmax of 4.7, and hypermetabolic nodules were observed in the lung, chest wall, thoracic vertebra, and pelvis. Due to the advanced stage of the tumor, US-CNB was performed to acquire a pathological diagnosis. The immunohistochemical staining suggested malignant melanoma. Of note, no primary tumor was revealed. Finally, the patient refused systemic therapy and died from tumor progression seven months later. Hence, CEUS and CEMRI is fundamental in the diagnosis of hepatic melanoma, and PET-CT is helpful in clinical staging. For controversial results, US-CNB is required to establish the pathological diagnosis.