Metastatic Lung Adenocarcinoma Presenting with Hypereosinophilia

Lung cancer is one of the most common malignancies in both male and female patients. It is classified into small cell lung cancers and non-small cell lung cancers. Lung adenocarcinoma is a subtype of non-small cell lung cancer and accounts for the highest prevalence of lung cancer. Eosinophils are white blood cells (WBCs) that originate from the granulocytic lineage. Hypereosinophilia is a rare condition characterized by an absolute eosinophil count (AEC) of more than 1500 cells/µL. This is different from eosinophilia, which is defined as an absolute eosinophil count of more than 500 cells/µL. Hypereosinophilia is associated with several conditions, including allergic disorders, helminth infections, rheumatologic disorders, and hematologic malignancies. Paraneoplastic eosinophilia is a rare finding in solid malignancies. Herein, we report the case of a 55-year-old male who presented with shortness of breath and chest pain and whose workup showed metastatic lung adenocarcinoma associated with hypereosinophilia in the absence of a primary bone marrow disorder.