An Overview of Diagnosis of Primary Autoimmune Hypophysitis in a Single Prospective Monocentric Experience

INTRODUCTION: Autoimmune hypophysitis (AH) is a rare disease with a not well known natural progression Aim: To collect representative data on clinical features of AH and better characterize the disease. PATIENTS AND METHODS: A monocentric prospective study was designed. AH affected patients, evaluated at our tertiary care Pituitary Unit from 2011 were enrolled. After ruling out other pituitary mass and secondary causes of hypophysitis, AH was the exclusion diagnosis. AH was classified as adeno-hypophysitis, pan-hypophysitis and infundibulo-neuro-hypophysitis according to clinical and neuroradiological findings. RESULTS: 21 patients met the inclusion criteria: 9 were diagnosed as adeno-hypophysitis, 4 as pan-hypophysitis and 8 as infundibulo-neuro-hypophysitis. Frequency of secondary hypoadrenalism overlapped in adeno-hypophysitis, pan-hypophysitis and infundibulo-neuro-hypophysitis. Growth hormone deficit and secondary hypogonadism occurred more frequently in infundibulo-neuro-hypophysitis as compared to adeno-hypophysitis and pan-hypophysitis (p = 0.009; p = 0.04). All cases of multiple pituitary secretion deficits occurred in cases of infundibulo-neuro-hypophysitis (p = 0.04). No correlation between hypophysitis subtypes and the anti-pituitary and anti-hypothalamus autoantibodies were found. A higher frequency of ENA and ANA antibodies was found in cases of pan-hypophysitis (respectively OR: 5.0 95% CI: 0.86-28.8; p < 0.001 and 1.8 95% CI: 1.1-3.2; p = 0.02) as compared to adeno-hypophysitis and infundibulo-neuro-hypophysitis. CONCLUSION: Infundibulo-neuro-hypophysitis should be taken into account in the aetiological diagnosis of hypopituitarism, particularly if associated with diabetes insipidus and in cases of growth hormone deficit, secondary hypogonadism or multiple hormone deficits. Contrast enhanced-MRI is crucial in the clinical and non invasive diagnosis of hypophysitis. A screening of auto-antibodies, particularly anti-ENA and anti-ANA, is strongly suggested, in the clinical contest of hypophysitis.