Lymphocytic Hypophysitis of Pregnancy Resulting in Hypopituitarism: A Distinct Clinicopathologic Entity

Two patients presented with abnormalities suggestive of pituitary adenoma; one during pregnancy and one in the postpartum period. However, pathologic examination of the pituitary showed extensive destruction by a lymphoplasmacytic infiltrate; no tumor was identified. Both patients developed hypopituitarism. We know of eight additional cases of lymphocytic hypophysitis, seven of which have been reported in the literature. In only three cases, including the two reported here, the diagnosis was established by biopsy. In each of those cases, the entity mimicked a pituitary tumor. This is the first report of electron microscopy of this lesion and the ultrastructural features support the previously suggested autoimmune etiology. The lesion has been described only in women and seven of ten patients were pregnant or postpartum at the onset. This fact and previously reported experimental evidence, including the identification of anti-prolactin cell antibodies, support our suggestion that lymphocytic hypophysitis associated with pregnancy represents a distinct clinicopathologic entity.