ESPE Abstracts

Introduction: Pituitary stalk interruption syndrome (PSIS) is a rare congenital abnormality of the pituitary gland. Perinatal injuries, defective organogenesis or rare mutations of HESX1, LHX4, OTX3 and SOX3 are proposed to be the cause of PSIS in familial cases. It is characterized by the triad of a very thin or interrupted pituitary stalk, an ectopic (or absent) posterior pituitary and hypoplasia or aplasia of the anterior pituitary. Typical features are tertiary hypothyroidism, hyperprolactinemia and other pituitary hormone deficiencies.

Objective and hypothesis: To present the clinical and hormonal characteristics of a patient with PSIS who was referred for primary amenorrhea.

Results: A 16-year-old female was referred for primary amenorrhea. She was born at term without a history of birth asphyxia. She had no chronic illness. Parents were not related and target height was 161 cm (0.17 SDS). There was no family member with delayed puberty or amenorrhea. On physical examination, height SDS was −1.49, weight SDS was 1.63, pubertal development was delayed (Tanner stage B2P3). Hormonal analysis revealed a normogonadotropic state with low E₂ levels, central hypothyroidisim, low IGF1 and persistently low prolactin levels. Pelvic ultrasonography revealed small ovaries and uterus for age. Karyotype was 46,XX. Pituitary MRI showed anterior pituitary hypoplasia, an ectopic posterior pituitary and absent pituitary stalk. According to the findings in MRI, the patient was diagnosed with PSIS. Results of GH provocation tests suggested GH deficiency, and a low dose ACTH stimulation test revealed a normal cortisol response.

Conclusion: We present a case of a PSIS with normogonadotropic amenorrhea and low prolactin levels. Despite the fact that this is a rare disorder, which typically presents with hyperprolactinemia, it should always be kept in the differential diagnosis of a patient with normogonadotropic amenorrhea and/or hypoprolactinemia.