MRI - Pituitary mass, histiocytosis X: This 46-year-old woman with a history of histiocytosis X presented with headache and blurred vision. Examination was significant for bilateral temporal visual field impairment. On the T1-weighted coronal post-contrast (left panel) and pre-contrast (right panel) images there is a heterogeneously enhancing lesion within the region of the pituitary gland with extension into the left cavernous sinus.