A Rare Presentation of a Malignant Melanoma Presenting as a Large Pulmonary Mass Causing Superior Vena Cava Obstruction

Abstract

A 50-year-old otherwise well man with a 20-pack year smoking history was referred for a computed tomography pulmonary angiogram (CTPA) to investigate progressive dyspnea and cough over several weeks. A large 16 cm solitary mass was discovered in the right hemithorax causing encasement of the superior vena cava (SVC) with an intraluminal obstructing SVC tumor thrombus. Initial CT did not reveal any further sites of distant metastatic disease for a presumed primary lung malignancy. However, a core biopsy revealed the mass to be the solitary presentation of a primary BRAF V600E positive malignant melanoma. Urgent initiation of molecular targeted therapy with combination tyrosine kinase inhibitors (dabrafenib (BRAF) / trametinib (MEK) inhibition) led to significant tumor regression, including of the extensive tumor thrombus.