Presentation
Diabetes insipidus
Patient Data
This contrast enhanced dynamic MR shows an absent posterior pituitary bright spot on the pre-enhanced T1WI.
The MR also shows a thick (3.8 mm, normal is < 2.4 mm), but normally enhancing pituitary stalk.
In absence of any other biochemical finding or significant clinical history, one would consider autoimmune disorder as the likely cause.
Case Discussion
There are several causes of central diabetes insipidus (DI). MR is performed to determine the cause. The presence of a thickened pituitary stalk in this case points towards the possibility of either inflammatory or autoimmune hypophysitis. When the inflammation is limited to the posterior pituitary, the condition may be termed as infudibuloneurohypophysitis. If the anterior pituitary is also involved (not seen in this case), the condition may be termed as infundibulohypophysitis (dropping the term "neuro"). Such kind of global involvement of the pituitary is seen in lymphocytic hypophysitis.
Although final cause of the pituitary stalk inflammation could not be established in this case, the MRI serves to demonstrate the prudent approach to a patient with central diabetes insipidus.
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