Endocrine Abstracts

Most of prolactin secreting tumors excellently respond to low doses of dopamine agonists (DAs). However, management of giant, invasive prolactinomas, partially or completely resistant to DAs is a challenge. Male patient was referred to endocrinologist in 2008, at the age of 63 years, presented with headaches, pressure sensation behind the left eye, decreased vision and fatigue for the last 2 months. In 1986 (at the age of 40 years) blurred vision had appeared for the first time and pituitary macroadenoma (prolactinoma) with endo-supra-infra-laterocellar growth was revealed. Decreased libido had started earlier. In 1986 partial adenomectomy with subsequent gamma radiation therapy were performed. For 6 years after this treatment he received bromocriptine (BRC), L-thyroxine and testosterone with no signs of tumour remnant growth. In 1993 he had discontinued BRC, had no complaints and was lost to follow-up until 2008. At examination in 2008 gynoid type of obesity (BMI 39 kg/m2) and pronounced hyperprolactinemia with prolactin (PRL) level of 66928 mU/l (ULN 360) were revealed. Macroprolactinemia was excluded. Pituitary MRI showed adenoma 38х41х40mm with intrasellar and left paracellar growth, invasion to sphenoid sinus, infratemporal space and cavernous sinus, surrounding left carotid artery. Considering location and extension of pituitary mass repeat surgery was not recommended, and cabergoline (CAB) was started from 0, 5 mg/week with stepwise dose increase. Under CAB treatment at increasing dose up to 3 mg/week PRL reduction from 66928 (ULN 360) to 1554 (ULN 407) mU/l was achieved by 2009. Pituitary MRI in 2010 showed a reduction of adenoma size to 29x27x25mm with signs of invasion. Unfortunately, further increase of CAB doses up to 5-7 mg/week along with correction of hypopituitarism was not effective. PRL level had increased up to 122000-172200 mU/l (ULN 407). Stereotactic radiation therapy in 2012, 2014 had also failed to stop further growth of macroadenoma (up to 86x43x55mm) with orbital invasion, compression of the left optic nerve and progressive visual deterioration. Patient had died in 2016. This case emphasizes the necessity of the permanent follow-up with continuous, usually lifelong administration of DAs in patients with macroprolactinomas after non-radical pituitary surgery. Initiation of CAB demonstrated dramatic (about 49 times) reduction of PRL level and positive MRI changes even in a patient with invasive giant prolactinoma. On condition of uninterrupted DAs treatment it would probably be possible to control hyperproplactinemia, improve patient’s quality of life, to prevent further growth of residual tumour, development of CAB resistance and visual impairment.