Oedema along the optic tracts due to pituitary metastasis

The MRI finding of oedema along the optic tract has been reported in patients with craniopharyngioma, as a useful diagnostic sign among common pituitary tumours. We report two patients with pituitary metastasis with this MRI finding. A 59-year-old woman and a 54-year-old man had diabetes insipidus and extraocular impairment due to a pituitary metastasis from adenocarcinoma of lung and colon, respectively. Several months later, they noticed rapidly deteriorating visual field and acuity impairment. MRI revealed enlarged pituitary mass accompanied by marked oedema along the bilateral optic tracts. To our knowledge, this is the first MRI report of oedema along the optic pathway due to pituitary metastasis. Our cases and review of literature indicate that this MRI sign is non-specific. Appearance of the oedema well corresponded to the initiation of visual complaint, which make a good contrast to reported clinical presentations of craniopharyngioma. Clinical significance and pathomechanism of this MRI sign are discussed.