Histology transformation-mediated pathological atypism in small-cell lung cancer within the presence of chemotherapy: A case report

BACKGROUND: The treatment of small-cell lung cancer (SCLC) has progressed little in recent years because of its unique biological activities and complex genomic alterations. Chemotherapy combined with radiotherapy has been widely accepted as the first-line treatment for SCLC. CASE SUMMARY: Here, we present a 68-year-old male smoker who was diagnosed with SCLC of the right lung. After several cycles of concurrent chemoradiotherapy, the tumor progressed with broad metastasis to liver and bone. Histopathological examination showed an obvious transformation to adenocarcinoma, probably a partial recurrence mediated by the chemotherapy-based regimen. A mixed tumor as the primary lesion and transformation from SCLC or/and tumor stem cells may have accounted for the pathology conversion. We adjusted the treatment schedule in accord with the change in phenotype. CONCLUSION: Although diffuse skeletal and hepatic metastases were seen on a recent computed tomography scan, the patient is alive, with intervals of progression and shrinkage of his cancer.