Summary
A patient with severe diabetes insipidus for 14 years was found to have an enlarged and eroded sella turcica with greatly reduced pituitary tissue on pneumo-encephalography. It is suggested that the permanent diabetes insipidus may have resulted from growth of an intrasellar tumour, which subsequently infarcted spontaneously. Thyroid and pituitary-adrenal function nevertheless remained good, which accounts for persistence of the diabetes insipidus.