An 86-year-old woman presented with chronic cough and chest pain. Computed tomography revealed two masses in the right lower lobe of the lung accompanied by multiple lymphadenopathies and metastasis to the rib. The pro-gastrin-releasing peptide (ProGRP) levels were notably elevated (888 pg/mL). Based on these findings, our initial clinical diagnosis was small-cell lung cancer. However, the pathological diagnosis turned out to be an atypical carcinoid. The patient was finally treated with everolimus. Clinicians should be aware that carcinoid tumours are sometimes difficult to distinguish from small-cell lung cancer with respect to high ProGRP levels and multiple metastases.