Giant Prolactinomas: An Experience From South India

Giant prolactinomas are large lactotroph adenomas, defined as those with maximum dimension of >4cm. They constitute <5% of all prolactin secreting tumors, and are more frequently seen in men. They present with features of hyperprolactinemia and hypopitutarism and are responsive to dopamine agonist therapies. In the current study we have shared our experience on management of giant prolactinomas over the last 15 years. We collected clinical data retrospectively from medical records of patients with giant prolactinoma managed at our institute over the last 15 years. This study describes the symptomatology, tumor characteristics and response to therapy. Our study included 21 patients with 15 males and 6 females. The mean age of presentation was 32 ± 10.3 years, ranging between 10 to 53 years. Vision defect was the predominant complaint (57%, 12 patients), followed by headache (52%, 11 patients). Erectile dysfunction was a presenting feature in 13% of men (2 patients) and amenorrhea/galactorrhea in 33% of women (2 patients). Seizure was seen in 10% of the patients (2 patients) and 10% (2 patients) were diagnosed with giant prolactinoma on evaluation for primary infertility. Tumor associated pituitary dysfunction manifested as hypogonadism in 67%, 14 patients, central hypothyroidism in 38%, 8 patients, and hypocortisolism in 1 patient. The median maximum tumor dimension was 4.4 cm with median basal PRL of 7168 ng/ml. Five patients underwent debulking surgery (24% of the patients) prior to endocrinology referral for indications such as apoplexy/raised intracranial tension. All patients received cabergoline and a mean dose of 2.1 ± 1.7 mg/week (range, 1-7 mg/week) was prescribed to attain a median nadir prolactin level of 48 ng/ml over a median period of 4 months (range, 1-40 months). The follow-up MRI data was analysed for 13 patients. Tumor shrinkage of >50% from the baseline was seen in all but 1 patient (92%) and 2 patients had disappearance of radiologically detectable tumor. Although giant prolactinomas have a greater tumor burden than the more common macroprolactinomas, the responsiveness to dopamine agonist therapy is excellent and surgical therapy is reserved for any exceedingly large tumors to relieve compression on vital structures.