Primary hypophysitis

Primary hypophysitis is a heterogenous inflammatory process of the pituitary that should be included in the differential diagnosis of space-occupying lesions of the sellar region. The etiology of primary hypophysitis has still not been fully elucidated, although an autoimmune origin is suspected. Histologically, primary hypophysitis includes three main different subtypes: lymphocytic, granulomatous and xanthomatous; the question of whether these are truly distinct entities or simply different expressions of the same disease remains unclear. The type and degree of lymphocytic infiltration determine the clinical and pathological symptoms (most frequently diabetes insipidus, hypopituitarism, headache and visual defects). If only the anterior pituitary is affected by infiltration, the entity is known as lymphocytic adenohypophysitis, when the posterior lobe and the infundibulum are infiltrated, lymphocytic-infundibuloneurohypophysitis, and if the infiltration is global, lymphocytic panhypophysitis. The importance of recognizing this entity lies in the possibility of obtaining a response to medical antiinflammatory therapy.