Metastatic BRAF V600E-Mutated Adenocarcinoma of the Lung Presenting as Extreme Neutrophilia and Eosinophilia

Abstract

Hematologic paraneoplastic syndromes with extreme neutrophilia and eosinophilia are very rarely associated with adenocarcinoma of the lung. We describe a case of a 57-year-old female who presented with neutrophil-and eosinophil-predominant hyperleukocytosis and hypoxic respiratory insufficiency. Bone marrow biopsy confirmed metastatic adenocarcinoma, similar to the biopsy-proven adenocarcinoma of the lung. She was administered one dose of cytotoxic chemotherapy with carboplatin and pemetrexed and started on leukoreductive therapy with hydroxyurea. Molecular testing revealed a BRAF V600E mutation and she was started on dabrafenib and trametinib with significant clinical improvement. This is the first reported case of metastatic BRAF V600E mutated non-small cell lung cancer presenting with extreme neutrophilia and eosinophilia treated with a combination BRAF and mitogen-activated extracellular kinase (MEK) inhibitor.