Endocrine Abstracts

Central diabetes insipidus (CDI) is an uncommon disorder characterised by a deficiency of arginine vasopressin. There are many causes of CDI including traumatic, infiltrative, inflammatory and neoplastic disorders of the pituitary or hypothalamus. CDI may be associated with a pituitary stalk lesion or thickening. Such thickening is commonly related to lymphocytic infundibular hypophysitis (LIH) or other granulomatous infiltrative disorders.

We present a series of four cases with symptoms of CDI, confirmed on testing, which we determined to be caused by pituitary stalk lesions. We will discuss each case in some detail and present the relevant associated radiology.

This case series serves to highlight the common themes of CDI but also the very important point that the aetiology of CDI may differ in each case and that consequently, investigation of the underlying cause must be systematic and thorough.

Case 1. A 22-year-old female presented 10/7 post-partum with polydipsia and polyuria. MRI showed the characteristic findings of bulky pituitary gland and stalk thickening with avid enhancement consistent with LIH. Management was conservative with desmopressin. Repeat MRI showed partial resolution.

Case 2. A 55-year-old man presented with 2/52 acute polyuria. MRI showed slight stalk thickening and poor delineation. Symptoms were controlled with DDAVP, repeat MRI revealed globular enlargement of the stalk consistent with pituicytoma.

Case 3. A 39-year-old man presented with 3/52 of gradual headache and flu-like symptoms, polydipsia and polyuria. Blood tests demostrated panhypopituitarism. MRI showed diffusely enlarged gland and an enhancing stalk lesion suggestive of LIH.

Case 4. A 21-year-old woman presented with thyrotoxicosis, confirmed on TFTs. She also c/o polydipsia and polyuria. CDI was confirmed. Initial MRI was normal. 3/12 later she developed headache and visual changes. Repeat MRI showed a pituitary stalk tumour. Surgery confirmed a germinoma.