Giant Prolactinoma in Men: Clinical Features and Therapeutic Outcomes

Abstract

The aim of the study was to evaluate the clinical features and long-term therapeutic outcome of giant prolactinoma (gPRLoma) in men and to compare them with those of a group of male patients with non-gPRL macroprolactinomas (non-gPRLomas). A retrospective and multicenter study of gPRLomas in men diagnosed in a 20-year period was performed. Clinical data and treatment outcome were registered. The diagnosis of gPRLoma was established when the maximal tumor diameter was ≥40 mm or the tumor had ≥20 mm of suprasellar extension associated to hyperprolactinemia (PRL>1000 ng/ml). Non-gPRLoma was considered when tumor diameter was ≥ 10 mm and<40 mm associated to hyperprolactinemia (PRL≥200 ng/ml). Twenty-three patients with gPRLoma (age 38.3±13.5 years) followed for at least 3 months (follow-up 87.1±60.5 months, range 3-211 months) were evaluated. A group of 42 patients with non-gPRLoma (age 42±16.6 years; NS; follow-up 89±65.9 months, range 3-222 months; NS) served as a control group. More than half (56.5%) of the gPRLoma patients were younger than 40 years at diagnosis. Visual disturbances were significantly more common in gPRLoma than in non-gPRLoma patients (65.2 vs. 25.6%; p=0.004). Prevalence of hypopituitarism was similar in both groups of patients (73.9% vs. 80.9%; gPRLoma vs non-gPRLoma; NS). Serum PRL concentrations were significantly higher in gPRLoma than in non-gPRLoma patients [median (IR), 3978 ng/ml (1179-9012) vs. 907 ng/ml (428-3119); p<0.001]. Maximum tumor diameter in gPRLomas was 4.8±0.8 cm and 2.4±0.7 cm in non-gPRLoma (p<0.001). All patients were treated with dopamine agonists (DA). Twelve (52.2%) gPRLoma patients and 32 (73.8%) non-gPRLoma patients were treated with DA as monotherapy (p=0.045). Surgery was used in 12 (52.2%) gPRLoma patients and in 12 (28.6%) non-gPRLoma patients (p=0.054). Lastly, radiotherapy was used in 5 (21.7%) gPRLoma patients and in 6 (14.2%) non-gPRLoma patients (NS). At last visit, PRL was similar in both groups of patients [16 ng/ml (4-30) vs. 11 ng/ml (4-25); gPRLomas vs. non-gPRLomas; ns] and tumor size decreased significantly (p<0.001) in both groups of patients. Clinical cure (maintained normoprolactinemia without therapy for>1 year and no radiological evidence of pituitary tumor) was achieved in 2 (8.7%) gPRLoma patients and in 2 (4.8%) non-gPRLoma patients (NS). gPRLomas in men are usually diagnosed at a mean age of 40 years, an age similar to that of non-gPRLomas. The only clinical difference with non-gPRLomas is their greater prevalence of visual disturbances. The therapeutic approaches and tumor outcomes were similar to those obtained in patients with non-gPRLomas. Complete cure in gPRLoma is rare, but similar to that achieved in non-gPRLomas, reached in less than 10% of patients.