Malignant lung melanoma mimicking mucoid impaction on imaging.

An asymptomatic 67-year-old man was referred to our clinic because of an abnormal shadow found on a chest Xray (Picture 1). Chest computed tomography showed the gloved finger sign, thus suggesting mucoid impaction (Picture 2). The lesion was diagnosed to be malignant melanoma by transbronchial lung biopsy (Picture 3). The patient was diagnosed to have malignant melanoma of unknown origin with lung, gastric, and bone metastases. The FDGuptake was also shown in the lung metastasis on positron emission tomography (Picture 4). Multiple nodules (1), and solitary nodules with a miliary pattern, and a lymphangitic carcinomatosis pattern (2), have also been reported as the imaging findings associated with lung metastases of malignant melanoma. However, the gloved finger sign, as observed in this case, is rare. In the present case, metastasis may have occurred via the lumen of the bronchus and then progressed lengthwise, thus resulting in such an image, but no abnormality in the bronchial mucosa was seen on bronchoscopy.