(12.07) An intriguing case of Thin Stalk and isolated Growth Hormone deficiency- Pituitary Stalk Interruption Syndrome

Pituitary stalk disorders are very rare cause of hypopituitarism. They include stalk interruption syndrome, duplication of the stalk, thinned stalk and thickened stalk. Here we describe a case of thin stalk presenting with growth retardation and delayed puberty.

Case(s) Description : A 14-year-old boy presented with short stature and under developed secondary sexual characteristics. His siblings and parents were healthy with normal height and pubertal development. He is a product of non-consanguineous marriage and his antenatal and perinatal period was uneventful. His developmental milestones were attained as per age. Normal scholastic performance and no behavioral abnormalities. General Examination revealed polydactyly of both hands. Anthropometric measurements revealed height SDS – 3.7SDS, weight SDS – 2.7SDS, US / LS :1.14. His stretched penile length is 3cm, bilateral Testicular Volume 4cc and had no axillary hair, pubic hair and no gynecomastia. Laboratory parameters showed stimulated GH 3.86, stimulated LH & FSH 10.25 and 3.88 mIU/ml respectively with total Testosterone < 2.5 ng/dl. MRI Pituitary revealed thin pituitary stalk with hypoplastic anterior pituitary & Ectopic posterior pituitary. A diagnosis of Pituitary stalk interruption syndrome was made and was started on GH replacement therapy, subsequent follow ups showed satisfactory improvement in growth.

Discussion : Pituitary stalk interruption syndrome (PSIS) is a congenital anatomical anomaly defined by the triad of thin or absent infundibulum (stalk), absent or hypoplastic anterior pituitary gland and ectopic posterior pituitary. Its clinical presentation is variable as per age, more commonly present with short stature and delayed puberty as in our case. The exact causes of PSIS are not fully understood, but it is believed to result from perinatal factors like mechanical trauma during birth, birth asphyxia. Genetic factors, particularly mutations in genes like LHX3/LHX4, PROP1, and HESX1, have also been implicated in its development. Additionally, PSIS is often associated with midline and extracranial malformations, such as cleft lip, palate abnormalities, optic nerve hypoplasia, and renal agenesis. Our case had bilateral post axial polydactyly of hands. The management of patients with pituitary stalk duplication varies according to the age of presentation, hormone deficiencies and the presence of other associated pathologies. Despite the fact that this is a rare disorder, it should always be kept in differential diagnosis of a patient presenting with short stature. Appropriate hormone replacement therapy and follow up for development of other endocrine deficiencies are critical in patients presenting in childhood.