Growth of a solitary pulmonary nodule after 6years diagnosed as oncocytic carcinoid tumour with a high 18-fluorodeoxyglucose (18F-FDG) uptake in positron emission tomography-computed tomography (PET-CT)

Abstract

Introduction: Pulmonary carcinoid tumour is low-grade neuroendocrine malignancy that is seen 1%-2% of all lung neoplasms. Oncocytic carcinoid type is a rarely seen variant of pulmonary carcinoids. As carcinoid tumours have hypometabolic activity, they usually have lower 18-fluorodeoxyglucose (18F-FDG) uptake than expected for lung carcinoma on positron emission tomography (PET).

Case report: A 45-year-old non-smoking man had a stable solitary pulmonary nodule followed for 6years; the tumour remained the same size (1.5×2.4cm) during this period. The patient was admitted to the hospital with complaints of repetitive sneezing and rhinorrhoea. He also experienced flushing and bronchospasm. His chest X-ray revealed a minimal increase in the size of the solitary pulmonary nodule (2.0×2.8cm). In PET-computed tomography (CT), the parenchymal nodule in the anterior segment of the right lung had a standard uptake value of 38.0mg/mL, which was interpreted as a malignant nodule. He underwent fibre-optic bronchoscopy, but cytology showed no evidence of malignancy. Right upper and middle bilobectomy was performed, and a pulmonary carcinoid tumour with an oncocytic subgroup was diagnosed. The diagnosis of carcinoid syndrome was further confirmed by an elevated 24-h urinary excretion of 5-hydroxyindoleacetic acid.

Conclusion: We present a rare case of an oncocytic carcinoid tumour with an increase in the size of a solitary pulmonary nodule after 6years' follow-up. In addition, PET-CT showed a very high 18F-FDG uptake in this patient, which is an unexpected finding with a pulmonary carcinoid tumour.