Introduction: Silent somatotroph Pituitary Neuroendocrine Tumours (PitNETs) are extremely rare (2−3% of surgically treated pituitary tumours) and data on their natural history and outcomes are scarce.
Aim: To review systematically the cases of these tumours presenting in our Centre.
Patients and methods: Patients with this diagnosis were identified from our Pituitary Registry and clinical/laboratory/imaging data were collected and analysed.
Results: Sixteen cases were identified [10 females−6 males, median age at diagnosis: 52 years (26−64)]. Two patients presented with apoplexy (13%), whereas in two, the tumour was found incidentally (13%). Visual field defects were detected in 69% of cases with available data. All tumours were macroadenomas; supra/para/infrasellar extension was present in 81%, 56% and 38%, respectively. Surgery was performed by transsphenoidal approach in 94% of cases and adjuvant radiotherapy was offered in three patients (19%) (45 Gy in 20 or 30 fractions). In all, except one case, there was partial tumour removal. During median follow-up of 12.1 years (0.25−26), seven patients had tumour regrowth (46.7% − one excluded due to short follow-up) at a median interval of 3.1 years (2.6−10.3) since surgery [50% of those treated solely by surgery (regrowth probability 55.6% at 5-years and 10-years) and 33.3% of those treated by surgery + radiotherapy]. Regrowths were managed by surgery (n=3), radiotherapy (n=1), surgery + radiotherapy (n=1) and observation (n=2). Two patients had second growth. None of the patients developed clinical acromegaly during follow-up.
Discussion/conclusions: In our series, the majority of silent somatotroph PitNETs had supra/parasellar extension. In comparison with historical data and within the constraints of our small sample size, the 10-years regrowth probability of those treated solely by surgery fall within the reported range for non-functioning PitNETs. Larger scale studies aiming to clarify whether this tumour subtype is characterised by aggressive clinical behaviour are needed.