Surgical Outcome and Treatment of Thyrotropin-Secreting Pituitary Tumors in a Tertiary Referral Center

OBJECTIVE

Thyrotropin (TSH)-secreting pituitary tumors are rare and typically present with hyperthyroidism. Here we report the diagnosis, treatment, and surgical outcomes in a series of patients with TSH-secreting pituitary tumors in a tertiary referral center.

METHODS

Descriptive retrospective study that included all patients with TSH-secreting pituitary tumors who underwent transsphenoidal surgery in the endocrinology and nutrition unit of the Virgen del Rocío University Hospital (Seville, Spain) between 2004 and 2016.

RESULTS

The mean age at diagnosis was 42.8 ± 17 years. The mean time from onset of symptoms to diagnosis was 13 ± 10 months. Four patients displayed symptoms indicating hyperthyroidism (1 suffered from tachycardia); 3 patients showed symptoms because of mass effect (visual impairment and headache) and 3 patients were diagnosed based on incidental findings after routine blood tests (high free thyroxine levels). Eight patients had macroadenomas, and 2 patients had microadenomas. Five patients underwent conventional pituitary surgery, and 5 patients underwent expanded endoscopic transsphenoidal surgery. Six patients achieved cure after surgery. The other patients received radiotherapy and/or treatment with somatostatin analogs. Analysis of somatostatin receptor (SSTR) expression by immunohistochemistry could be performed in 6 tumors.

CONCLUSIONS

Our results confirm the clinical and hormonal heterogeneity caused by TSH-secreting pituitary adenomas. Surgery is considered the first choice of treatment for these tumors. We observed surgical cure rates similar to those reported in recent published series. SSTR2 and SSTR3 are highly expressed in TSH-secreting pituitary adenomas. Our results suggest that somatostatin analog treatment may be also helpful in the treatment of TSH-secreting pituitary adenomas.

E-cadherin expression is associated with somatostatin analogue response in acromegaly

Acromegaly is a rare disease resulting from hypersecretion of growth hormone (GH) and insulin‐like growth factor 1 (IGF1) typically caused by pituitary adenomas, which is associated with increased mortality and morbidity. Somatostatin analogues (SSAs) represent the primary medical therapy for acromegaly and are currently used as first‐line treatment or as second‐line therapy after unsuccessful pituitary surgery. However, a considerable proportion of patients do not adequately respond to SSAs treatment, and therefore, there is an urgent need to identify biomarkers predictors of response to SSAs. The aim of this study was to examine E‐cadherin expression by immunohistochemistry in fifty‐five GH‐producing pituitary tumours and determine the potential association with response to SSAs as well as other clinical and histopathological features. Acromegaly patients with tumours expressing low E‐cadherin levels exhibit a worse response to SSAs. E‐cadherin levels are associated with GH‐producing tumour histological subtypes. Our results indicate that the immunohistochemical detection of E‐cadherin might be useful in categorizing acromegaly patients based on the response to SSAs.

Association between dopamine and somatostatin receptor expression and pharmacological response to somatostatin analogues in acromegaly

Acromegaly is a hormonal disorder resulting from excessive growth hormone (GH) secretion frequently produced by pituitary adenomas and consequent increase in insulin‐like growth factor 1 (IGF‐I). Elevated GH and IGF‐I levels result in a wide range of somatic, cardiovascular, endocrine, metabolic and gastrointestinal morbidities. Somatostatin analogues (SSAs) form the basis of medical therapy for acromegaly and are currently used as first‐line treatment or as second‐line therapy in patients undergoing unsuccessful surgery. However, a considerable percentage of patients do not respond to SSAs treatment. Somatostatin receptors (SSTR1‐5) and dopamine receptors (DRD1‐5) subtypes play critical roles in the regulation of hormone secretion. These receptors are considered important pharmacological targets to inhibit hormone oversecretion. It has been proposed that decreased expression of SSTRs may be associated with poor response to SSAs. Here, we systematically examine SSTRs and DRDs expression in human somatotroph adenomas by quantitative PCR. We observed an association between the response to SSAs treatment and DRD4, DRD5, SSTR1 and SSTR2 expression. We also examined SSTR expression by immunohistochemistry and found that the immunohistochemical detection of SSTR2 in particular might be a good predictor of response to SSAs.