6823 A Puzzling Case: Complete Regression of Pituitary Macroadenoma

Abstract Disclosure: N.T. Mazengia: None. D.R. Vangipuram: None. S.K. Majumdar: None. Introduction: The natural course of nonfunctioning pituitary macroadenomas remains poorly understood, largely because the majority are surgically treated [1]. There are a few case reports describing the spontaneous regression of nonfunctioning pituitary macroadenomas. Here we describe a case of pituitary macroadenoma which completely regressed following childbirth and two months of cabergoline therapy. Case Presentation: A 25-year-old female presented with bilateral nipple discharge and persistently elevated prolactin levels ranging from 31µg/liter to 45.9 µg/liter (NV <25 µg/L). She did not have any signs and symptoms of hypo or hypersecretion of the pituitary hormones. All her pituitary hormone levels were within normal range. Initial MRI revealed a pituitary mass measuring 9x13x9mm (AP, TR, CC). Given her lack of symptoms, the decision was made to follow up without any intervention. A repeat MRI after one year showed the size of the mass to be 11x13x11mm. Two years after her initial diagnosis, the patient had a spontaneous pregnancy, during which she remained asymptomatic with normal pituitary hormone levels. She had Cesarean delivery at term with no complication. She was lost to follow-up for about two years after childbirth then presented with breast discomfort and galactorrhea at which time, she was started on cabergoline. A subsequent MRI done two months after the start of cabergoline showed asymmetric fullness of the pituitary gland on the right with no discrete measurable lesion. Conclusion: We currently lack a comprehensive explanation for the regression observed in our patient. Silent ischemia may have played a role, particularly considering the natural increase in pituitary gland size during pregnancy. We are not sure if the regression can be solely attributed to the two months of cabergoline treatment. In asymptomatic patients diagnosed with nonfunctioning pituitary macroadenoma, tumor regression can potentially occur through either a "wait and watch" strategy or medical management using dopamine agonists, specifically cabergoline. However, the use of cabergoline as a primary treatment for asymptomatic nonfunctioning pituitary adenoma warrants further investigation. This is especially crucial given that, in most cases, nonfunctioning pituitary macroadenomas tend to increase in size during follow-up without any intervention. References: 1. Dekkers, O.M., A.M. Pereira, and J.A. Romijn, Treatment and follow-up of clinicallynonfunctioning pituitary macroadenomas. J Clin Endocrinol Metab, 2008. 93(10): p. 3717-26. Presentation: 6/1/2024