Endocrine Abstracts

Introduction: Giant prolactinomas are rare pituitary tumours, more frequently found in men (9:1), defined by an unusually large size (>4 cm), significant extrasellar extension and prolactin levels above 1000 ng/ml. Although dopamine agonists (DA) are the first-line treatment, combined therapy with DA and surgery, or rarely radiotherapy, may be necessary particularly when tumour volume control is not achieved.

Case presentation: A 60-year-old woman, was referred to our Endocrinology department (March 2016) due to a prolactinoma. The diagnosis had been made in another institution, at patient age 25, because of amenorrhea, galactorrhoea and headaches. At age 20 she had had a full-term pregnancy and two voluntary miscarriages between 20 and 25-year-old. She has a medical history of hypertension, dyslipidaemia, depression and obesity (submitted to gastric bypass surgery). Her family history was unremarkable. When diagnosed with prolactinoma, bromocriptine was prescribed, latter switched to cabergoline in unknown dosages. She had a poor compliance to treatment and was lost for follow-up between 2008–2016. In March 2016, due to change of city of residency, her new general practitioner referred to us and she reported a progressively visual impairment. CT scan revealed a large pituitary mass (31×25×47 mm), with infra and suprasellar growth, invading sphenoid and cavernous sinuses and compressing optic chiasm. Laboratory evaluation revealed hyperprolactinemia (7010 μg/l; normal range: 5–23 μg/l) and FSH/LH deficiency. Bitemporal hemianopsia was confirmed by visual campimetry. Bromocriptine was titrated up to 30 mg/day and subsequently changed to cabergoline (3 mg/week) due to persistently high prolactin levels and lack of tumour size reduction. After 3 months of cabergoline, prolactin remained high (3804 ng/mL) and MRI showed a tumor size of 31×48 mm. She underwent transsphenoidal surgery in November 2016 with no visual improvement. Histopathological examination revealed a prolactin adenoma without cytological atypia or mitotic figures, negative p53 immunoreactivity and Ki67 index <2%. The patient missed several appointments and keeps postponing surgical reintervention.She is currently medicated with cabergoline 3 mg/week, maintaining high level of prolactin (1749 ng/mL) and persistence of intrasellar tumour (21×20×20 mm) with optic chiasm compression.

Conclusion: In this case, the poor patient compliance could have been responsible for clinical outcome. Histopathological features of the tumour did not anticipate an aggressive behaviour and immunostaining analysis of quantitative expression of dopamine receptors could have been elucidative of inefficacy of medical therapy. In the future, radiotherapy may be considered if uncontrolled tumour progression occurs after additional surgical debulking.