We report a 54-year-old man, affected by myeloproliferative neoplasm, JAK2 V617F-positive of 13 years duration, who acutely presented with a third cranial nerve palsy; neuroradiology documented a space-occupying lesion at the level of the sellar, upper clival and right parasellar regions, that was sub-totally removed with a trans-sphenoidal approach.