Endobronchial pigmented mass in a patient with primary malignant melanoma of the lung: A case report.

Malignant melanoma (MM) commonly presents as a primary skin tumor and respiratory MM cases are almost all metastatic. Primary lung MM (PMML) is quite rare, especially when manifested as an endobronchial pigmented mass, its diagnosis is relatively difficult and MM has a poor prognosis. Only a few cases have been described previously and the pathologic features, clinical behavior and therapeutic options are not well established. The present study reports the case of a 72-year-old female patient with PMML who denied any history of tumors. The patient complained of chest pain and coughing for 2 weeks. Chest computed tomography (CT) revealed a mass in the right upper lobe and an enlarged mediastinal lymph node. Positron emission tomogram-CT suggested a hypermetabolic tumor. To confirm the diagnosis, the patient underwent a transbronchial forceps biopsy and endobronchial ultrasound-guided transbronchial needle aspiration, which confirmed the diagnosis of PMML. Genetic testing identified a V600E mutation, so the patient received treatment with dabrafenib plus trametinib. PMML is extremely rare and is easily misdiagnosed as lung cancer due to its nonspecific clinical manifestations and imaging features. The diagnosis of PMML remains challenging due to its morphologic and immunophenotypic variability. Targeted therapy is a good option for advanced PMML patients with V600E mutations.