Objective: To describe an uncommon initial manifestation of well-differentiated follicular carcinoma of the thyroid in an unusual metastatic site.
Methods: We present clinical, laboratory, and imaging findings in our patient and review related data from the literature.
Results: A young healthy woman presented with headache and diplopia. Magnetic resonance imaging of the brain showed a complex mass in the sellar region. Endocrine evaluation was remarkable only for a modestly high serum prolactin level. Transsphenoidal biopsy of the sellar mass revealed metastatic follicular thyroid carcinoma. On subsequent examination, a thyroid nodule was palpated. She underwent total thyroidectomy and ablative therapy with 131I, after which her symptoms gradually subsided and the sellar mass ultimately decreased in size. Although well-differentiated thyroid cancer generally manifests as a thyroid nodule, metastatic disease is present at the time of initial assessment in approximately 1% of cases, and the lungs and the skeleton are the most frequent sites of involvement. Only a few cases of thyroid cancer metastasizing to the sella have been reported. Described cases occurred mainly in elderly patients with previously diagnosed thyroid cancer. The most common malignant tumors that metastasize to the sella and pituitary are lung cancer in men and breast cancer in women. Metastatic tumors frequently manifest with cranial nerve palsies or diabetes insipidus and occur in elderly patients.
Conclusion: Follicular thyroid cancer can manifest initially as a distant metastatic tumor in young patients. Metastatic lesions should always be in the differential diagnosis of a sellar mass, even in young patients.