Primary pulmonary melanoma diagnosed by semi-rigid thoracoscopy.

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A 47-year-old woman was admitted to our hospital with chief complaints of back pain and exertional dyspnea. She had no history of disease or any current skin lesions. Left pleural effusion, and intrathoracic and liver tumors were observed on her chest computed tomography scan (Fig 1). The semi-rigid thoracoscopic findings showed a bulky black mass and multiple scattered small black nodules (Fig 2). Histological findings revealed a malignant melanoma. The patient received four cycles of immunotherapy with nivolumab (3 mg/kg) and was administered intrathoracic paclitaxel (100 mg/m2) once. However, the tumors increased steadily and were judged as progressive. The patient died three months after diagnosis. Malignant melanoma mostly occurs in the skin and sometimes in the mucosa, such as the eyes.1 Primary malignant melanoma of the lung is uncommon, accounting for 0.01% of all lung tumors.2 Primary malignant melanoma of the liver has not previously been reported. In the present case, lesions were not found in the skin or mucosa but in the lung, liver, and pleura. The masses in both the lung and liver were single and bulky. Nodules lay scattered in the pleura and seemed to be pleural dissemination. Therefore, the lung or liver was considered the site of the primary lesion. Jensen and Egedorf described clinical criteria for the diagnosis of operable localized primary pulmonary melanoma;3 however, these are not diagnostic criteria for pulmonary primary melanoma with distant metastasis. We clinically diagnosed that the lung was likely the primary lesion, but could not completely exclude the possibility that the liver was the primary lesion. This is a rare image of primary pulmonary melanoma observed by thoracoscopy. The authors thank Mr. Brent Bell for reading the manuscript. No authors report any conflict of interest.