Ectopic TSH-secreting pituitary adenoma of the vomerosphenoidal junction

We describe an unusual case of ectopic TSH-secreting pituitary adenoma arising from the vomerosphenoidal junction.

A 52-Year-old man with a long-standing history of hyperthyroidism was referred to the University Hospital in September 2001 because of increasingly disabling symptoms of nasal obstruction. For the past 18 Years the patient had complained of palpitations, hypertension, weight loss, and nervousness. A presumptive diagnosis of Graves' disease was made. Treatment with methimazole was begun, but the patient was lost to follow-up. On admission, physical examination revealed signs of hyperthyroidism and a large diffuse goiter. Tests of thyroid function showed inappropriate secretion of TSH with hyperthyroidism. Both a TSH-secreting pituitary adenoma and resistance to thyroid hormone could be taken into account. There was no evidence of pituitary tumour by magnetic resonance imaging (MRI), but a large space-occupying lesion involving the nasal cavity and the nasopharynx was incidentally discovered. INTERVENTATION AND TECHNIQUE: Using an endoscopic endonasal approach, the tumour was removed en bloc together with the sphenoid floor, sphenoid rostrum, bony septum, and part of the soft palate mucosa. Histological features and immunophenotype were those of a TSH-secreting tumour.

Although exceedingly rare, ectopic TSH-secreting pituitary tumour should be borne in mind in cases of inappropriate secretion of TSH with hyperthyroidism and no evidence of pituitary tumour by computed tomography and/or MRI when a mass located along the migration path of the Rathke's pouch is demonstrated by radiological examination. To our knowledge, this is only the second reported case in the literature.