A case report of pulmonary combined small cell carcinoma with enteric adenocarcinoma

BACKGROUND: Combined small cell lung cancer (CSCLC) is rarely reported, which accounting for only 2% to 5% of all lung cancers. And enteric adenocarcinoma is also a rare subtype of non-small cell lung cancer (NSCLC) whose histomorphology is very similar to lung metastatic colorectal cancer. CASE DESCRIPTION: We report a case with both small cell lung cancer (SCLC) and enteric adenocarcinoma for the first time. The patient was admitted to our hospital due to the left lung mass after a routine examination. She underwent computed tomography scan and needle biopsy, which showed the tumor consisted of two different components (70% SCLC and 30% enteric adenocarcinoma). The mixed density nodules were also observed in the right lung’s lower lobe, and positron emission tomography-computed tomography (PET-CT) showed an increase of standard uptake value (SUV) greater than 2.5 in the right lung. Imaging and pathology experts agreed that the nodules of right lung were metastatic lesions after multi-disciplinary treatment (MDT). Considering the epidermal growth factor receptor (EGFR) p.L861Q mutation, the patient received gefitinib and EP chemotherapy, and she responded well to the combination therapy. At last follow-up, the progression-free survival (PFS) reached 11 months, and the adverse effects were clinically acceptable and tolerable. CONCLUSIONS: This case report provides direct evidence for EGFR-tyrosine kinase inhibitor (TKI) and EP chemotherapy is effective and useful in the treatment of CSCLC patients with enteric adenocarcinoma.