Endocrine Abstracts

Background: The glands most commonly affected in MEN1 are parathyroid, pituitary and pancreas. Pancreatic neuroendocrine tumours (pNETs) are of foregut origin, but a number of other so-called ’foregut carcinoid tumours’ may also occur in MEN1, including tumours of bronchial, thymic, and gastrointestinal origin. Reported rates of prevalence of these latter tumours vary from 2% for thymic and bronchial carcinoids, to 10% for gastric carcinoids. Thymic carcinoids have been reported as aggressive in nature, whereas bronchial carcinoids are thought to be mostly indolent, with no effect on increased mortality in MEN1.

Aims: To evaluate the prevalence and characteristics of carcinoid tumours in current patients under follow-up with MEN1 at a tertiary referral centre.

Methods: Data were collected from case notes, histopathology reports, and cross-sectional imaging.

Results: Forty-six patients were under current follow-up with MEN1, 17 males and 29 females, mean age 53.7 years (range 18–79). Thirty-one foregut carcinoids were identified in 27 patients, of which 25 were pNETs. Six patients had non-pancreatic foregut carcinoids, five of which were intrathoracic (three bronchial, one thymic, and one indeterminate) and one was of gastric origin. Hyperparathyroidism was present in all six patients, four had a concurrent pNET (two gastrinomas and two non-secretory), and two had pituitary lesions. The three bronchial carcinoids included one successfully resected hormone-secreting tumour, and two non-secreting bronchial carcinoids, both of which showed malignant potential. One thymic carcinoid was successfully resected and the inderminate mediastinal mass is currently under investigation, but shows features of neuroendocrine carcinoma potentially of thymic origin.

Discussion: In this contemporary series of non-related MEN1 patients, the prevalence of foregut carcinoids was 59%, and of non-pancreatic foregut carcinoids 13% (predominantly bronchial), which is higher than in most reported series. In contrast to previous studies, non-secretory bronchial carcinoids showed aggressive characteristics in these patients. Current consensus guidelines suggest 1–2 yearly surveillance imaging with CT or MRI to detect intrathoracic carcinoids. Further prospective studies are required to guide decisions regarding prophylactic resection of asymptomatic pulmonary nodules.