Background: Pituitary adenomas are rare in children and adolescents. The response of macroprolactinomas to dopamine agonists (DA) in this age group has been less extensively studied than in adults.
Objective: We retrospectively analyzed data on a large cohort of young patients with macroprolactinomas.
Patients and methods: Patients aged younger than 20 years at macroprolactinoma diagnosis and seen in three tertiary referral centers between 1983 and 2013 were studied by analyzing their clinical and genetic (AIP and MEN1) characteristics. Hormonal and tumoral responses to DA were analyzed, and the patients' status at their last visit, after a mean (±SD) follow-up of 8.2 ± 5.8 years, was assessed.
Results: The cohort comprised 77 patients (26 males, 51 females). Mean age at diagnosis was 16.1 ± 2.5 years (range, 4.5-20 y). In both sexes, the most frequent revealing symptom was a pubertal disorder (49%), followed by visual problems (24%) and growth retardation (24%). Basal prolactin (PRL) levels and maximal tumor diameter were significantly higher in boys than in girls (7168 ng/mL, 202-40 168 vs 1433 ng/mL, 115-20 000, P = .002; and 33 ± 14 mm, 15-64 vs 19 ± 9 mm; 10-50, P < .001, respectively). PRL levels normalized in 74% of the patients treated with DA. A mutation of AIP or MEN1 was found in 14% of the patients. Factors associated with resistance to DA were young age, higher PRL levels, larger volume, and the presence of a MEN1 (but not an AIP) mutation.
Conclusion: Macroprolactinomas are rare below the age of 20 years, mainly occurring in girls and during adolescence. Like adults, young patients are very sensitive to DA, which should therefore be considered the first-line treatment. DA resistance is associated with a higher PRL level and larger tumor size, both parameters being closely linked together. About 14% of these young patients have an AIP or MEN1 mutation, this latter being an independent predictor of DA resistance.