PRL and hyperpituitarism: In premenopausal patients, the proportion of patients with hyperprolactinaemia and the mean serum PRL level were significantly higher in those diagnosed with fibroepithelial tumours (FETs) and in younger patients (aged < 35 years) than in those with non-neoplastic lesions and in those aged ≥ 35 years (both p < 0.05).