[Atypical pulmonary carcinoid tumor with abnormal elevation of serum gastrin-releasing peptide precursor: report of a case].

We report a rare case of atypical pulmonary carcinoid tumor accompanied by elevation of serum gastrin-releasing peptide precursor (ProGRP). A 55-year-old male presented to our hospital with a history of bloody sputum. The level of serum ProGRP was elevated to 781 pg/ml (normal < 46 pg/ml). Chest computed tomography (CT) revealed a solitary pulmonary tumor in the left lower lobe with sub-carinal lymph node enlargement. Transbronchial lung biopsy showed a pulmonary carcinoid, therefore left lower lobectomy with mediastinal lymph node dissection was performed. ProGRP decreased to normal level 1 month after operation. Histopathological diagnosis showed an atypical pulmonary carcinoid tumor.