Although visceral metastases of malignant melanoma are common, pleural metastases without pulmonary parenchymal metastatic involvement is rare. Here we describe a case of recurrent disease that presented as a large pleural effusion without concomitant lung involvement.
An otherwise healthy 37 year-old fair-skinned man presented with progressive dyspnea. He had a history of a single scalp melanoma resected fourteen years prior with no complications or known spread. He did not receive adjuvant chemotherapy. On exam, he appeared slightly uncomfortable with normal vital signs and an SpO2 of 96% on 2 liters/min nasal cannulaO2. His left hemithorax was dull and without breath sounds. The remainder of his exam was normal. His radiograph revealed left hemithoracic opacification with contralateral mediastinal shift. Thoracentesis revealed a lymphocytic exudate with negative cultures and cytology. Pleural biopsy was non-diagnostic of microbes or tumor. One month later he again required thoracentesis of a lymphocytic exudate for symptoms of dyspnea. CT scan of the chest showed nodules lining the left parietal and visceral pleura and enlarged left hilar and subcarinal lymph nodes. PET scan of the chest demonstrated increased radiotracer uptake consistent with metastatic spread in all of these areas with no uptake in the lung itself. Video-assisted thoracoscopic exploration showed the pleural surfaces to be studded with tumor. Biopsy of this tissue revealed melanoma. Skin survey did not reveal any new nevi or lesions.DISCUSSION: Malignant exudative pleural effusions are commonly found in lung and breast carcinomas and in lymphoma. Melanoma is known to easily metastasize to the lung parenchyma through hematogenous and lymphangitic spread. These cases can be associated with lymphocytic malignant pleural effusions. However, effusions associated with isolated pleural metastases are rare, especially so long after primary diagnosis. The ipsilateral lymphadenopathy without radiotracer uptake in the lung in this case is consistent with pleural lymphatic drainage without concomitant pulmonary parenchymal spread.
Metastatic melanoma is an extremely difficult disease to detect, partly because visceral metastatic spread does not manifest itself early. It is extremely challenging to treat because it is strongly resistant to chemotherapy and radiation. In this case recurrent metastatic melanoma to the pleura resulted in a massive exudative pleural effusion in an unusual manifestation of the disease. The long period of time between initial diagnosis and the presentation of metastatic symptoms in this case underlines the difficulty in detection and management of this disease.
A.D. Sotelo, None.