BACKGROUND Primary melanoma of the lung is a rare tumor that represents 0.01% of primary lung tumors, with only 40 cases reported in the literature. Mucosal melanomas are tumors with a biological and clinical presentation that differs from that of cutaneous melanomas; therefore, the therapeutic approach differs as well. Survival rates of patients with primary melanoma of the lung are much lower than those of patients with cutaneous melanoma, and there are no diagnostic or treatment guidelines for this entity. Radical surgery is the treatment of choice when disease is resectable. The effectiveness of current established treatments for cutaneous melanoma (eg, immunotherapy and targeted therapy) is unknown in this particular subgroup. CASE REPORT We present the case of a patient who presented with cough and hemoptysis. The fiberoptic bronchoscopy revealed an endobronchial mass and the computed tomography images suggested an unresectable mass. The patient was initially diagnosed with an unresectable primary lung melanoma with a clinical stage IIIB (T4N2M0). This lesion achieved partial response after treatment with Pembrolizumab, which allowed radical surgery to be performed, achieving complete resection with negative margins and adequate postoperative evolution. Despite the delays in our health care system, she is currently alive and disease-free more than 24 months after diagnosis. CONCLUSIONS Immunotherapy can reduce the size of mucosal melanoma to the point that it can be resectable and this therapeutic approach increases the survival opportunities of these patients.