Abstract #1401381: Rare Case of Asymptomatic Multiple Sclerosis Lesions in Hyperprolactinemia

Abstract

Hyperprolactinemia is associated with established multiple sclerosis (MS) and MS progression/relapse. An association between hyperprolactinemia and asymptomatic MS lesions, also known as radiologically isolated syndrome (RIS), has not been reported. A 29-year-old African American man presented with gynecomastia during a primary care visit. Medical history included prediabetes, hypertension, and obesity. He denied galactorrhea, decrease in libido, blurred vision, fatigue, enlarged hands/feet, hyperpigmentation, depression, easy bruising, skin changes, polyuria, and any neurological symptoms. His physical exam was unremarkable except for bilateral gynecomastia and obesity. Laboratory results revealed elevated prolactin 30.6 ng/mL. Thyroid function test was normal. Magnetic resonance imaging (MRI) brain showed normal pituitary gland size with a 0.3-cm rounded hypo-enhancing region, enhancement of the left optic nerve, and areas of abnormal T2/FLAIR lesion involving the juxtacortical and subcortical white matter in the left temporal region. Enhancements in the right occipitotemporal region and a small juxtacortical lesion in the medial inferior left frontoparietal region were also observed. The patient was referred to endocrinology. His only complaint was fatigue, and physical exam was unremarkable. Repeat prolactin was higher than before at 78 ng/mL. TSH was elevated at 6.44 mIU/mL with a free T4 of 1.03 ng/dL. Labs including ANA, AQP 4, Lyme, HIV, JC virus, and syphilis panel were negative. He was started on cabergoline 0.5 mg twice weekly for treatment of hyperprolactinemia. He was also started on levothyroxine for fatigue, which was attributed to subclinical hypothyroidism. Neurology initiated treatment for MS with diroximel fumarate. Follow-up in 2 months showed a prolactin level of 1 ng/mL and a normal TSH and free T4. The patient will be followed with MRI pituitary surveillance at 1 year and 5 years. This is a very rare case of hyperprolactinemia associated with RIS. The decision to treat the patient for MS was made to prevent or delay potential clinical symptoms or progression to overt disease. One study has noted a 34% risk of conversion of RIS lesions to the first clinical event of MS in 5 years, especially with risk factors like young age and male gender. However, it is still debatable whether RIS lesions progress and should be treated, given that medications used to treat MS are associated with possible side effects including allergic reaction. Follow-up will focus on presence of new neurological symptoms concerning for MS and change in the size of the pituitary lesion.