Endocrine Abstracts

Background

Multiple Endocrine Neoplasia type 1 (MEN 1) is a genetic syndrome caused by inactivating mutations of the menin gene, which predisposes to the development of endocrine tumors. The causative mutations, clinical manifestations, and age of tumor development are highly variable. The objective of this study is to describe the characteristics of patients with MEN1 in our hospital.

Material and methods

We performed an observational, descriptive, unicentric study of patients diagnosed with MEN1 followed in the Department of Endocrinology of La Paz University Hospital in the last 10 years. Results of categorical variables were expressed in absolute or relative frequencies and those of continuous variables in mean and standard deviation.

Results

Eleven patients (7 women/4 men) with an average age of 39.4±16.0 years old were diagnosed with MEN1. Eight patients (72.7%) were the index case, and the other three were diagnosed during genetic screening. 63.6% of the patients had other affected relatives. Patients of the same family, who expressed the same mutation, differed in the clinical presentation. The most common manifestation was primary hyperparathyroidism (PH), which appeared in all the patients. The age at diagnosis of PH was 38.3±15.1 years and was the first manifestation in two patients. After surgery (subtotal parathyroidectomy or total parathyroidectomy with forearm auto-implantation), 63.6% of patients were cured, 18.2% developed transient hypoparathyroidism, and 27.3% permanent hypoparathyroidism. 81.8% of patients had pancreatic neuroendocrine tumors (pNET) (45.5% non-functioning pNET, 9.1% concomitant insulinoma and gastrinoma, 9.1% insulinoma, and 18.2% gastrinoma). Five patients had multifocal pNETs. pNETs were localized except for two patients, one patient with gastrinoma had lymph node metastases, and another with non-functioning pNET had liver and splenic metastases. The average age at diagnosis of pNET was 39.3±15.3 years, and it was the first manifestation in one patient. After surgery, 77.7% of patients with pNET developed insulin-dependent diabetes mellitus. 72.7% of patients had a pituitary adenoma (27.3% non-functioning adenoma, 36.4% prolactinoma, and 9.1% mixed prolactin-and-GH secreting adenoma). The average age at diagnosis of pituitary adenoma was 31.5±11.8, being the first clinical presentation in three patients. Other manifestations were an adrenal adenoma in three patients, lipomas in two patients, and thymoma in one patient.

Conclusions

It is a small but representative cohort of patients with MEN1. Our results are similar to those described in the literature. Thymoma is an atypical presentation rarely reported in MEN1 and was present in one patient of our cohort.