SUN-085 Ectopic Posterior Pituitary and Associated Hypopituitarism: A Case Series

Abstract Disclosure: A. Sehgal: None. D.M. Watashi: None. S.T. Sharma: None. INTRODUCTION: An ectopic posterior pituitary (EPP), predominantly at the median eminence, arising from abnormal embryonic development, is a rare entity with an incidence of 0.5 per 1,000,000 births. Although commonly associated with growth hormone (GH) deficiency, other pituitary hormone abnormalities can also be seen. We describe three cases with EPP and varying pituitary hormone dysfunction, emphasizing the need for close long-term follow-up of these patients. CASE DESCRIPTION: Case 1: 30-year-old male, born at full term, required NICU care for hypoglycemia. He was initially diagnosed with secondary adrenal insufficiency, central hypothyroidism, and hypogonadism and treated with hydrocortisone and levothyroxine. MRI Pituitary showed an EPP, absent pituitary stalk, and a small pituitary gland. He later developed GH deficiency and AVP deficiency and was placed on GH and desmopressin as well. Case 2: A 34-year-old male presented at age 1 year with failure to thrive. Diagnosed with GH deficiency and initiated on treatment. At age 2 years, he developed central hypothyroidism and was placed on levothyroxine. MRI Pituitary at age 6 years revealed an EPP and hypoplastic pituitary stalk. He later developed central adrenal insufficiency and central hypogonadism, prompting replacement therapy. Has not shown any evidence of AVP deficiency. Case 3: 42-year-old female diagnosed with GH deficiency at age 5 years. MRI showed an EPP and a hypoplastic infundibulum. Later developed secondary amenorrhea and was diagnosed with hypogonadotropic hypogonadism as well as central hypothyroidism. MRI Pituitary showed an EPP and hypoplastic pituitary stalk. She has not shown any signs of adrenal insufficiency or AVP deficiency. DISCUSSION: EPP results from defective neuronal migration and may occur in isolation or with stalk anomalies. While isolated GH deficiency is the most frequent presentation of EPP, it can be associated with panhypopituitarism or another individual pituitary hormone dysfunction. Posterior pituitary function frequently remains intact. Congenital hypopituitarism is classified as either hypothalamic or pituitary in origin, with associated gene defects like HESX1. It is often associated with hypoplasia of the anterior pituitary and the pituitary infundibulum, but the underlying mechanism is still not well understood. CONCLUSION: EPP is a rare condition that should be considered in patients diagnosed with hypopituitarism. MRI is the gold standard imaging modality to identify this condition. All three of our patients were diagnosed with EPP in childhood, either with isolated GH deficiency or with coexistent other pituitary hormone deficiencies. These patients require lifelong follow-up with an endocrinologist. Treatment consists of hormone replacement, with the main goals of alleviating symptoms and preventing complications. Presentation: Sunday, July 13, 2025