Primary Amenorrhea as the initial Presentation of a Cystic Pituitary Macroadenoma with Severe Hyperprolactinemia: A Case Report

Introduction Primary amenorrhoea is an uncommon presentation of pituitary tumours in adolescents. Hyperprolactinaemia may suppress the hypothalamic–pituitary–gonadal axis, leading to delayed pubertal development and amenorrhoea. Case description An 18-year-old girl presented with primary amenorrhoea and had previously received oestrogen and progesterone without aetiological evaluation. She subsequently developed headaches and galactorrhoea. Hormonal assessment revealed severe hyperprolactinaemia (1766 ng/mL) with suppressed gonadotropin. Pituitary MRI showed a large mixed solid–cystic sellar mass. She was treated with cabergoline, resulting in rapid prolactin normalisation, spontaneous menstruation, and marked tumour regression on follow-up imaging. Discussion This case illustrates that prolactin-secreting pituitary macroadenoma may present with isolated primary amenorrhoea and minimal neurological signs. Early endocrine evaluation is essential to avoid delayed diagnosis and inappropriate empirical hormonal therapy. Dopamine agonists therapy is highly effective in achieving biochemical and radiological remission even in large cystic lesions.