Endocrine Abstracts

A 45-year-old lady presented with two years history of galactorrhea and tiredness. The galactorrhea had been getting progressively worse. Initially it was on squeezing the breast but later on it came on spontaneously. She had to change her bra more than twice a day. She was also feeling unduly tired. She got occasional headaches but no visual disturbances. The period was regular and she was on no regular medications. She is married and has three children, the youngest is four year old. Physical examination was unremarkable apart from easily expressible milk on squeezing the breast.

The first prolactin level was 753 (0–600) but on repeat it was 552. Pituitary profile showed normal LH (3.5), FSH (7.5), Estradiol (1271) and cortisol (397). However the TSH was low normal 1.45 (0.4–5.0) in the face of lowish fT₄ 11.9 (12–23) and low normal fT₃ 4.7 (4–7.8). The IGF1 was persistently low at 67 and 66 (94–252).

MRI pituitary showed 10 mm well defined mass in the pituitary stalk without signs of compression on the optic chiasm.

The differential diagnosis of pituitary stalk adenoma is: tumours (low grade glioma, craniopharingioma, rathke’s cleft cyst, germinoma, metastatic lesion, lymphoma, ectopic prolactinoma and ectopic non-functioning pituitary adenoma) and granulomatous diseases (langerhan’s cell histiocytosis, sarcoidosis and TB). By examining the radiological features our initial differential diagnosis was either ectopic non-functioning pituitary adenoma or ectopic prolactinoma.

She was started on gabergolin 0.5 mg twice weekly for symptomatic relief with plan to repeat the MRI scan in 18 months time to see if it has an impact on the tumour size.

Clinic review was made four months later. The galactorrhea was ceased completely but she was still feeling tired. Repeat blood tests showed prolactin 72, TSH 1.63, fT₄ 13.5, fT₃ 4.9, cortisol 410 and IGF1 84.

Because of the on going tiredness and persistently low IGF1 we performed ITT. It revealed a borderline GH response (i.e GH response <20 but >10 mU/l).

Repeat MRI scan after 18 months showed no change in the size of the pituitary stalk adenoma. This result suggested that the tumour is likely to be an ectopic non-functional pituitary adenoma. The highish prolactin level might be due to stalk pressure effect. Stalk adenoma is a rare condition with clinical challenges especially in terms of the radiological features of the differential diagnosis and the treatment of the resultant pituitary hormonal disturbance. Surgery is not advisable. However biopsy sometimes needed to establish the nature of the tumour. Our patient needs perhaps life long follow up with continuing monitoring of the tumour size and the pituitary function.