Multiple endocrine neoplasia type 1: from isolated symptoms to a syndromic diagnosis (clinical case)

Background. Multiple endocrine neoplasia syndrome (MEN) is a hereditary disease with an autosomal dominant mode of inheritance, characterized by the development of tumors in several endocrine organs against the background of germline mutations in tumor suppressor genes. Despite the presence of characteristic clinical and genetic markers, the diagnosis of type 1 MEN is often delayed. Cases with non‑classical manifestation present particular challenges.

Description of a clinical case. Patient P., 29 years old, with verified MEN type 1 syndrome. Has been under dynamic monitoring by an endocrinologist at her place of residence since 2022. The development of endocrine pathology was gradual, demonstrating a typical evolution of the disease with sequential involvement of the parathyroid glands, the adenohypophysis, and the pancreas. The disease manifested as primary hyperparathyroidism with laboratory‑confirmed hypercalcemia (total calcium – 2.74 mmol/L) and elevated parathyroid hormone levels (up to 28.09 pmol/L). Subsequently, a mammosomatotropinoma of the pituitary gland was diagnosed, accompanied by clinically significant hyperprolactinemia (prolactin levels up to 1226 mU/L, monomeric prolactin up to 402 mU/L), laboratory signs of acromegaly (growth hormone – 13.2 ng/mL, somatomedin‑C – 451 ng/mL), and characteristic clinical manifestations (increased foot size, galactorrhea). During instrumental examination, multiple solid masses in the pancreas were additionally identified; they were assessed as neuroendocrine tumors, and calculi were found in both kidneys. The patient underwent subtotal parathyroidectomy (on 24.10.2025) and endoscopic transsphenoidal removal of a mammosomatotropinoma at the V.A. Almazov National Medical Research Center (on 22.12.2025), with normalization of hormonal parameters in the postoperative period.

Conclusion. The presented clinical observation demonstrates the typical evolution of MEN type 1 syndrome – from the manifestation of primary hyperparathyroidism to the formation of a complete classical triad involving the adenohypophysis and the pancreas. A distinctive feature of this case was the combination of hyperprolactinemia and acromegaly within the framework of a mammosomatotrophinoma, which required a comprehensive assessment of the function of the anterior pituitary lobe. The presented case illustrates the need for doctors who treat young patients with combined endocrine pathology to develop syndromic clinical thinking.

1. Marx S.J. Multiple endocrine neoplasia type 1: clinical and genetic features. Endocrine Reviews. 2018; 39 (2): 165–215. DOI: https://doi.org/10.1210/er.2017-00135

2. Salimkhanov R.Kh., Eremkina A.K., Bagirova Kh.V., et al. Multiple endocrine neoplasia type 1 syndrome: an analysis of data from 102 patients from 43 fa­ milies in the population of the Russian Federation. Problems of Endocrinology. 2026; 72 (1): 13–22. DOI: https://doi.org/10.14341/probl13642 (in Russ.)

3. Bibik E.E., Aboysheva E.A., Matyushkina A.S., et al. Non-classical manifestation of multiple endocrine neoplasia type 1 syndrome. Endocrine Surgery. 2023; 17 (3): 61–70. DOI: https://doi.org/10.14341/serg12815 (in Russ.)

4. Katsobashvili I.A., Pigarova E.A., Dzeranova L.K. A clinical case of multiple endocrine neoplasia type 1 syndrome. Endocrine Surgery. 2023; 17 (4): 43. DOI: https://doi.org/10.14341/serg12866 (in Russ.)

5. Dedov I.I., Melnichenko G.A., Mokrysheva N.G., et al. Draft clinical guidelines for the diagnosis and treatment of primary hyperparathyroidism in adult patients. Endocrine Surgery. 2022; 16 (4): 5–54. DOI: https://doi.org/10.14341/serg12790 (in Russ.)

6. Rozhinskaya L.Ya., Dzeranova L.K., Belaya Zh.E. Primary hyperparathyroidism: modern approaches to diagnosis and treatment. Problems of Endocrinology. 2020; 66 (3): 4–12. DOI: https://doi.org/10.14341/probl12462 (in Russ.)

7. Markarova E.V., Kogoniya L.M., Gurevich L.E., et al. Successful use of somatostatin analogue biotherapy in the treatment of a patient with multiple endocrine neoplasia type 1. Meditsinskii sovet. 2023; 17 (11): 166–71. DOI: https://doi.org/10.21518/ms2023-242 (in Russ.)

8. Petrov Yu.A., Kupina A.D. Complications of the gestation period in patients with multiple endocrine neoplasia type 1 syndrome. Consilium Medicum. 2020; 22 (6): 15–8. DOI: https://doi.org/10.26442/20751753.2020.6.200140 (in Russ.)

9. Pylina S.V., Elfimova A.R., Gorbacheva A.M., Eremkina A.K. Features of bone pathology in primary hyperparathyroidism associated with multiple endocrine neoplasia type 1 syndrome. Osteoporosis and Bone Diseases. 2022; 25 (3): 101–3. DOI: https://doi.org/10.14341/osteo13077 (in Russ.)

10. Rebrova D.V., Rusakov V.F., Chernikov R.A., et al. Secondary osteoporosis in multiple endocrine neoplasia type 1 syndrome. Osteoporosis and Bone Diseases. 2022; 25 (3): 105. DOI: https://doi.org/10.14341/osteo13081 (in Russ.)

11. Bagirova Kh.V., Spasskaya O.Yu., Kim E.I., et al. Genetic profile of parathyroid gland formations: lifting the veil of secrecy. Problems of Endocrinology. 2025; 71 (2): 35–44. DOI: https://doi.org/10.14341/probl13543 (in Russ.)

12. Dedov I.I., Melnichenko G.A., Dzeranova L.K., et al. Clinical guidelines "Hyperprolactinemia" (project). Obesity and metabolism. 2023; 20 (2): 170–88. DOI: https://doi.org/10.14341/omet13002 (in Russ.)

13. Kravchuk E.N., Tsoi U.A., Sereda S.S., Grineva E.N. An individual approach to the treatment of prolactinoma in a patient with multiple endocrine neoplasia type 1 syndrome. Russian Journal of Personali­ zed Medicine. 2022; 2 (4): 97–102. DOI: https://doi.org/10.18705/2782-3806-2022-2-4-97-102 (in Russ.)