An extremely rare case of small-cell lung cancer harboring variant 2 of the EML4-ALK fusion gene

Anaplastic lymphoma kinase (ALK) fuses echinoderm microtubule-associated protein-like 4 (EML4) to acquire a transforming activity in lung adenocarcinomas. However, the presence of an EML4-ALK fusion gene in other lung cancer histologies is an extremely rare phenomenon. A 43-year-old female was referred to our department due to dyspnea on effort and left back pain. Computed tomography (CT) showed a large mass in the upper lobe of the left lung and a massive left pleural effusion, while a CT-guided needle biopsy confirmed a diagnosis of small-cell lung cancer (SCLC). Surprisingly, the tumor was genetically considered to harbor the EML4-ALK fusion gene (variant 2). Although the patient underwent two regimens of cytotoxic chemotherapy for SCLC, she died approximately seven months after the administration of first-line chemotherapy. Our analysis of 30 consecutive patients with SCLC for EML4-ALK revealed that two patients, including the current patient and a patient we previously reported, harbored the EML4-ALK fusion gene.