Black Pleural Effusion: A Unique Presentation of Metastatic Melanoma

Metastatic melanoma is a rare form of skin cancer, but one that comes with a high mortality rate. Pulmonary involvement is frequently seen in metastatic melanoma with only 2% of malignant melanoma patients with thorax metastasis presenting with pleural effusions. Herein, we report an extremely rare case of black pleural effusion from thoracic metastasis of cutaneous malignant melanoma. A 74-year-old man with known metastatic melanoma presented with a 1-month history of worsening lower back and hip pain and was found to have extensive osseous metastatic disease and multiple compression fractures. The patient underwent an uneventful kyphoplasty; however, the following day, he became acutely hypoxic and tachypneic with increased oxygen requirements. Radiographic evaluation revealed new bilateral pleural effusions. Bedside thoracentesis revealed a densely exudative, lymphocyte-predominant black effusion. Cytological examination showed numerous neoplastic cells with melanin deposition. A diagnosis of thoracic metastasis of malignant melanoma was established based on the gross and microscopic appearance of the pleural fluid. To the best of our knowledge, this is the first reported case of black pleural effusions secondary to metastatic melanoma in the United States. Despite the rarity of this presentation, it is important to determine the etiology of the black pleural effusion and to keep metastatic melanoma as a differential diagnosis.