Bromocriptine-sensitive acidophil-stem-cell adenoma co-secreting growth hormone and prolactin - A case report
RV D'Costa & WJ Kalk
We report a 28-year-old man who presented initially to our ENT department with 3-year history of intermittent epistaxis subsequently found to have an extensive acidophil-stem-cell adenoma, rare pituitary tumours usually unresponsive to dopamine agonists requiring radiotherapy and somatostatin analogues in resistant cases.
He was clinically acromegalic, demonstrating an elevated Growth Hormone (GH) 17.9 milliunits per litre (normal 0-5.5) and Insulin like Growth Factor-1 (IGF-1) 81.3 nanomoles per litre (normal 14-48), non-suppressible GH to an oral hyperglycaemic challenge. Prolactin hugely elevated (109,000 milli-international units per litre) low gonadotrophins and testosterone; pituitary adrenal axis was normal.
Initial MRI showed an extensive tumour expanding the sphenoid sinus, dipping anteriorly into the nasal cavities, laterally around the carotid arteries and engulfing the optic nerves but sparing the chiasm. Despite its extensiveness, perimetry was normal.
The polyp was biopsied and confirmed histologically as an acidophil-stem-cell adenoma with immuno-positivity for Prolactin but not for other anterior pituitary hormones.
Within the 6 months of starting Bromocriptine there was normalisation of Prolactin, GH, IGF-1 and repeat GH suppression test is now normal. Follow-up imaging showed considerable shrinkage in tumour size and resolution of the suprasellar extension. He remains well on long term Bromocriptine.
This case illustrates a rare GH and Prolactin co-secreting pituitary acidophil-stem-cell adenoma, unusually responsive to Bromocriptine. These usually are associated with marked local invasion, tending to be resistant to dopamine agonists, with radiotherapy and somatostatin analogues suggested in resistant cases. The high Prolactin at presentation and preponderance of its staining on histology may help to identify a subset of tumours that respond to Bromocriptine. Remarkably, GH and IGF-1 levels normalised despite the absence of GH staining on immunostaining. Another learning point is that one should be constantly aware of atypical presentations of pituitary tumours as was in this case with epistaxis.