Developmental anomalies of the thyroid gland may result in ectopic gla
ndular tissue. We report a unique case of ectopic thyroid tissue withi
n the pituitary fossa and sphenoid sinus, associated with a lingual th
yroid gland, The aetiology of this ectopic tissue is postulated to be
ascent of primitive thyroid endoderm at the time of formation of Rathk
e's pouch. (C) Pearson Professional Ltd 1997.