Clinical Characteristics of 16 Patients with Pituitary Tumor Incidentally Detected by 18F-Fluorodeoxyglucose PET-CT (18F-FDG PET-CT)

ABSTRACT

BACKGROUND: It is uncommon to unexpectedly discover pituitary tumor as a hypermetabolic lesion on an 18F-FDG PET-CT scan for the evaluation of an unrelated disease when the patient does not show neurological or endocrine signs and symptoms. METHODS: We retrospectively analyzed the medical records of 16 patients with pituitary tumor that was detected incidentally on 18FFDG PET-CT at the Korea Cancer Center Hospital from January 2002 to September 2009. We analyzed their clinical features in detail. RESULTS: On 35,505 18F-FDG PET-CT scans, 16 (0.045%) patients were diagnosed with pituitary incidentaloma. They underwent 18FFDG PET-CT for the evaluation of the state of malignancy. All of them had no signs and symptoms related to pituitary tumor. The average age of the patients was 63.3 +/- 12.0 years (49-85 years). Eleven patients were men and 5 were women. The mean diameter of the tumor was 17.9 +/- 5.7 mm. Most of the pituitary incidentalomas were macroadenoma. The result of tumor morphologic evaluation by the Hardy classification was as follows 6 grade IV, 1 grade III, 3 grade II and 1 grade I. The mean standardized uptake value of the tumor was 10.6 +/- 6.7. Ten patients had endocrine evaluation and they showed a normal hormone level. Among 16 patients, 4 patients received TSA and they were diagnosed with pituitary adenoma. CONCLUSION: This study showed that pituitary incidentaloma discovered on 18F-FDG PET-CT was extremely rare. It was almost all non-functioning macroadenoma and this showed relatively high FDG uptake.