Endocrine Abstracts

JOINT1362

Objectives: Prolactinomas are pituitary adenomas that usually respond well to treatment with dopamine agonists with reduction in both prolactin levels and tumor size. Additionally, patients with autoimmune diseases, such as systemic lupus erythematosus (SLE), have been shown to have elevated prolactin levels. We describe an interesting patient with a prolactinoma who responded biochemically to dopamine agonists, but the tumor size remained resistant to treatment. The course was complicated by evolution of an autoimmune presentation questioning the cross talk between prolactin and autoimmunity.

Case Presentation: A 17-year-old female was referred to pediatric endocrinology for primary amenorrhea and headaches. Biochemical investigation identified hyperprolactinemia with prolactin levels of 1234 ng/ml with undetectable gonadotropin levels and pituitary imaging suggested a macroprolactinoma measuring 1.2 x1.3 x1.5 cm, with a cystic component. Treatment was initiated with cabergoline, leading to a reduction in prolactin levels to 24.8 ng/ml after 6 weeks and onset of menses after 3 months. Over the subsequent 3 years, even though prolactin levels significantly reduced, the reduction in the size of the tumor was not significant with the latest measurements of 1 x 1 x 1.2 cm with persisting cystic component with serum prolactin levels of 112 ng/ml. At the age 19 years, 2 years into treatment with cabergoline, the patient developed arthralgia with positive ANA levels with a working diagnosis of SLE. The patient also tested positive for thyroglobulin and thyroid peroxidase antibodies, indicative of Hashimoto’s thyroiditis.

Discussion: A cystic prolactinoma, a less common variant, may present with discrepancy between the degree of hyperprolactinemia and tumor size. Some prolactinomas may also be resistant to treatment with dopamine agonists questioning the presence of a nonfunctioning adenomatous tissue. Hyperprolactinemia has been linked to the pathogenesis of several autoimmune disorders. Although there is some evidence of interaction between hyperprolactinemia and autoimmunity, the exact mechanisms and directionality remain unclear. Patients with SLE, in particular, have been shown to have concurrent hyperprolactinemia, with some cases showing a positive correlation between serum prolactin levels and severity of autoimmune disease. Rare patients have been described with SLE and prolactinoma.

Conclusions: This is a patient with cystic prolactinoma that responded poorly to tumor size reduction despite significant improvement in prolactin levels. The clinical course was complicated by onset of arthralgia with a working diagnosis of SLE. There appears to be a complex interplay between hyperprolactinemia and autoimmunity. Future research should aim to unravel the mechanisms underlying this interaction.