Lymphoplasmacytic hypophysitis associated with immunoglobulin G4.

We present the unusual case of a 33-year-old woman who presented with a 2 year history of amenorrhoea and an expanding sellar lesion. Initial MRI revealed a lesion in the pituitary fossa, thought to be a pituitary adenoma. One year later, the lesion had enlarged by 5mm, with associated enhancement of the dura of the planum sphenoidale and pituitary stalk. Histopathology revealed a lymphocytic and plasma cell inflammatory infiltrate suggestive of lymphoplasmacytic hypophysitis associated with immunoglobulin G4.