Giant Prolactin-Secreting Pituitary Adenoma: A Case Report and Literature Review

Prolactinomas are the most common functional pituitary adenomas in the pediatric population, though they remain rare overall. Male adolescents often present with larger and more aggressive tumors than female adolescents, with delayed symptoms such as visual disturbances, headaches, and hypogonadism due to the absence of early hormonal signs. We report the case of a 15-year-old previously healthy male patient who presented with a one-month history of severe frontal headache, followed by blurred vision and vomiting. On examination, he exhibited bilateral mydriatic pupils unresponsive to light, left eye outward deviation, ataxic gait, and asthenic appearance. Brain MRI revealed a large sellar mass suggestive of an invasive pituitary adenoma. Laboratory evaluation showed extreme hyperprolactinemia (50,260.9 ng/mL) and central hypothyroidism, leading to the diagnosis of a giant invasive prolactinoma. He was treated with cabergoline and levothyroxine. Due to neuropsychiatric symptoms (hallucinations, insomnia, and agitation), aripiprazole and melatonin were added. No evidence of apoplexy or intracranial hypertension was found. Craniotomy surgery was performed successfully. Clinical improvement was observed, but the patient was lost to follow-up. This case illustrates the classical presentation of giant prolactinoma in a male adolescent, emphasizing the size-prolactin correlation and the importance of early detection and medical treatment. Neuropsychiatric symptoms can emerge as a result of tumor mass effect or dopaminergic therapy. Long-term follow-up is essential to evaluate treatment response and prevent endocrine and developmental complications. Genetic testing for MEN1 or AIP mutations should be considered in young patients with aggressive pituitary adenomas.