Papillary thyroid carcinoma metastatic to the pituitary gland

Many malignancies may present with metastases to the pituitary gland. The a ssociation of thyroid carcinoma with pituitary metastases is, however, very rare. This report describes two patients in whom metastases from a papilla ry thyroid carcinoma to the pituitary gland resulted in panhypopituitarism with blunted endogenous thyrotropin (TSH) production following withdrawal o f levothyroxine. Both required the use of recombinant human TSH prior to ra dioiodine therapy. Symptoms of hypopituitarism may be difficult to distingu ish clinically from those of hypothyroidism in the setting of levothyroxine withdrawal. Clinicians should be aware of the clinical and biochemical man ifestations of this rare association.