title: Is the incidence of differentiated thyroid cancer increased in patients with thyrotropin-secreting adenomas? Report of three cases from a large consecutive series.
abstract: BACKGROUND
  Patients with a thyrotropin-secreting pituitary adenoma (TSHoma) are exposed to unregulated and inappropriately high levels of thyrotropin (TSH). Given the rarity of this condition, it is not known whether this chronic TSH stimulation of the thyroid gland might represent a risk factor for the development of differentiated thyroid cancer (DTC). We analyzed the incidence of DTC in a large cohort of patients with TSHomas.
  
  
  METHODS
  The study population consisted of all consecutive patients who underwent neurosurgery for a TSHoma between 1990 and 2013. Criteria for the diagnosis of TSHoma in patients without previous thyroid ablative procedures included elevated free thyroid hormones and normal/high serum TSH concentrations, presence of a lesion at magnetic resonance imaging (MRI), and abnormal response of TSH to at least one dynamic test. Patients who had received thyroid ablative procedures were required to have a pituitary lesion on MRI and TSH levels not suppressed while on levothyroxine therapy at doses causing elevation of free thyroid hormone levels.
  
  
  RESULTS
  Sixty-two patients (32 females, 30 males) underwent surgery for a TSHoma at our center. Among them, 3 patients had a coexistent diagnosis of DTC with an estimated incidence of 4.8%. In 2 patients, DTC was diagnosed during the evaluation for suspected TSH-dependent hyperthyroidism, whereas in the third patient, diagnosis of DTC preceded the detection of the pituitary tumor.
  
  
  CONCLUSIONS
  The elevated incidence of DTC in patients with TSHoma suggests a possible role of TSH hypersecretion in the development of thyroid tumors. A formal high-resolution ultrasound of the thyroid is recommended in patients diagnosed with a TSHoma, especially if a long history of the pituitary tumor is suspected. Moreover, suspicion about the presence of TSHoma should be raised by the lack of suppression of TSH levels despite adequate doses of levothyroxine after thyroidectomy for DTC.
authors: 1 Pituitary Unit, Department of Neurosurgery, Istituto Scientifico San Raffaele, Università Vita-Salute , Milan, Italy .
authors: Francesca
authors: F
authors: Perticone
authors: Francesca
authors: F
authors: Pigliaru
authors: Stefano
authors: S
authors: Mariotti
authors: Luca
authors: L
authors: Deiana
authors: Lino
authors: L
authors: Furlani
authors: Pietro
authors: P
authors: Mortini
authors: Marco
authors: M
authors: Losa
mesh_terms: D000236:Adenoma / Q000097:blood / Q000453:epidemiology* / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood / Q000378:metabolism*; D002454:Cell Differentiation; D005260:Female; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D062606:Tertiary Care Centers; D013960:Thyroid Function Tests; D013964:Thyroid Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D013972:Thyrotropin