This case describes a 32-year-old mother of two with an unusual and challenging presentation of acromegaly. The patient did not have the classical features of acromegaly, but presented with elevated prolactin (2653mIU/L), oligomenorrhoea and galactorrhoea. She had an elevated IGF-1 139nmol/L and growth hormone 30mIU/L, which failed to suppress on oral glucose tolerance. Initial MRI brain showed a solid-cystic macroadenoma (47 x 22 x 19mm) with optic chiasm compression and bilateral cavernous sinus involvement. Formal visual field testing was normal.
The patient underwent surgical resection followed by stereotactic radiotherapy (50.4Gy in 18 fractions). Histopathology showed positive immunohistochemistry for chromogranin, growth hormone and prolactin. Despite multimodal treatment including lanreotide 120mg monthly and cabergoline 0.5mg weekly, her acromegaly remains resistant with persistently elevated IGF-1 and GH.
In patients with acromegaly, 30-40% have hyperprolactinaemia, which may represent either ‘stalk effect’ or true co-secretion from mammosomatotroph cells in the pituitary1,2. In cases of growth hormone and prolactin co-secretion compared to growth hormone hypersecretion alone, adenomas are larger and classical acromegalic features are less pronounced2. There is increased menstrual disorders and galactorrhoea leading to earlier presentation in women2. It is unclear if cosecretion of prolactin significantly alters morbidity and mortality in acromegaly.
In the treatment of acromegaly, current guidelines recommend surgical management as first line with adjuvant radiotherapy or medical therapy in residual disease3. Somatostatin analogues (SSA) are commonly used for medical therapy. Pasireotide, a second generation SSA and pegvisomant (a growth hormone receptor antagonist) have achieved good outcomes3. Dopamine agonists also have a role, with prolactin co-secretion a positive predictor of response3. Combination therapy with SSA and pegvisomant is reported3 and a recent case report induced biochemical remission with combination pasireotide, pegvisomant and cabergoline4. This case is an unusual presentation of acromegaly and it is hoped that with the use of immunohistochemical markers including SSTR expression to predict response to medical therapy and the use of newer agents will result in biochemical remission.