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Open access

Christopher W Rowe, Kirsten Murray, Andrew Woods, Sandeep Gupta, Roger Smith and Katie Wynne

Metastatic thyroid cancer is an uncommon condition to be present at the time of pregnancy, but presents a challenging paradigm of care. Clinicians must balance the competing interests of long-term maternal health, best achieved by iatrogenic hyperthyroidism, regular radioiodine therapy and avoidance of dietary iodine, against the priority to care for the developing foetus, with inevitable compromise. Additionally, epidemiological and cellular data support the role of oestrogen as a growth factor for benign and malignant thyrocytes, although communicating the magnitude of this risk to patients and caregivers, as well as the uncertain impact of any pregnancy on long-term prognosis, remains challenging. Evidence to support treatment decisions in this uncommon situation is presented in the context of a case of a pregnant teenager with known metastatic papillary thyroid cancer and recent radioiodine therapy.

Learning points:

  • Pregnancy is associated with the growth of thyroid nodules due to stimulation from oestrogen receptors on thyrocytes and HCG cross-stimulation of the TSH receptor.

  • Thyroid cancer diagnosed during pregnancy has not been shown to be associated with increased rates of persistent or recurrent disease in most studies.

  • There is little evidence to guide the management of metastatic thyroid cancer in pregnancy, where both maternal and foetal wellbeing must be carefully balanced.

Open access

Viral Chikani, Duncan Lambie and Anthony Russell

Summary

Metastases to the pituitary gland are an uncommon complication of thyroid cancer. They resemble pituitary neoplasms posing a diagnostic challenge. We present a case of an aggressive non-radioiodine avid papillary thyroid cancer with recurrent pituitary metastases and a review of the literature. A 70-year-old woman with a history of papillary thyroid cancer and bony metastases presented with symptoms of hypoadrenalism and peripheral vision loss. Magnetic resonance imaging showed a large pituitary mass impinging on the optic chiasm. She underwent transsphenoidal resection followed by 131I ablation. Post-therapy scintigraphy showed no iodine uptake in the sellar region or bony metastases. Histology of the pituitary mass confirmed metastatic papillary thyroid cancer. Fifteen months later, she had a recurrence of pituitary metastases affecting her vision. This was resected and followed with external beam radiotherapy. Over 2 years, the pituitary metastases increased in size and required two further operations. Radioactive iodine was not considered due to poor response in the past. Progressively, she developed a left-sided III and IV cranial nerve palsy and permanent bitemporal hemianopia. There was a rapid decline in the patient's health with further imaging revealing new lung and bony metastases, and she eventually died 8 months later. To our knowledge, this is the first case of pituitary metastases from a radioiodine-resistant papillary thyroid cancer. Radioiodine-resistant metastatic thyroid cancer may exhibit rapid aggressive growth and remain poorly responsive to the currently available treatment.

Learning points

  • Differentiated thyroid cancer (DTC) has an excellent prognosis with <5% of the cases presenting with distant metastases, usually to lung and bone.

  • Metastasis to the pituitary is a rare complication of DTC.

  • The diagnosis of pituitary insufficiency secondary to pituitary metastases from DTC may be delayed due to the non-specific systemic symptoms of underlying malignancy and TSH suppression therapy for thyroid cancer.

  • The imaging characteristics of metastases to the pituitary may be similar to non-functioning pituitary adenoma.

  • Radioiodine refractory metastatic thyroid cancer has significantly lower survival rates compared with radioactive iodine-avid metastases due to limited therapeutic options.