A child with growth retardation

A 7-year-old boy presented to the pediatric endocrinologist because of a downward trend on his height growth chart (-2SD) starting at the age of 2-3 years. Apart from his short stature, he had no other development delays. Laboratory tests showed an isolated borderline growth hormone (GH) deficiency.

The T1-weighted images shows a small pituitary fossa with hypoplasia of the anterior pituitary (Green arrow figure 2). The height of the anterior pituitary was approximately 3 mm. Absence of the normal high signal from the posterior pituitary in the sella turcica. The posterior pituitary is located against the median eminence of the hypothalamus (Red arrow figure 2). The pituitary stalk was hardly visible with only a pencil-thin line that could be suspected (Blue arrow figure 2).

Only around 50% of the patients with an isolated borderline GH deficiency, show abnormalities on MRI. The children without structural abnormalities often have less severe deficiencies and their blood levels often normalize when they reach adulthood. Many physicians doubt whether these children really have a deficiency at all and whether they need hormonal replacement therapy. [1]

Most children with abnormalities on MRI show one are all three characteristic features of pituitary stalk interruption syndrome (PSIS). Our case is a fine example of PSIS which is characterized by an ectopic posterior pituitary, a thin or interrupted pituitary stalk and hypoplasia or aplasia of the anterior pituitary. Only in a minority of cases the triad is present. It must be considered as a spectrum. The normal height of the anterior pituitary in children ranges on average from 5mm at birth to 6mm at 20 years of age. For the pituitary stalk a measurement of <1mm is considered pathologic. The more pronounced the MRI findings are, the more severe the hormone deficiencies are and the more likely they will persist in adulthood. These patients benefit the most from the hormonal replacement therapy. [2-5]

PSIS has an estimated incidence of 0.5 in a million births. More and more it is considered as a congenital defect since genetic research has identified several mutations associated with a familial form of PSIS. PSIS can be associated with midline defects (microcephaly, agenesis of the corpus callosum, optic nerve hypoplasia…) further supporting a developmental defect. PSIS causes a GH deficiency in almost all cases. The other pituitary hormones are variably affected with hyperprolactinemia being the most common. The function of the posterior pituitary is generally preserved. Depending on the severity and the extend of the hormonal deficiency’s symptoms can already appear in infancy short after birth with hypoglycemia, hypotonia, abnormal genitalia, prolonged icterus… In less severe cases symptoms involve mainly growth retardation or late puberty. Since these characteristics and the hormonal blood levels are highly variable also amongst the normal population, physicians use MRI to further decide which patients need replacement therapy. [1,6]

Apart from PSIS, other conditions such as several tumours, trauma, iatrogeneous, can cause variable hormone deficiencies in children. The most common being a Rathke’s cleft cyst and a craniopharyngioma. These cases are almost always associated with multiple hormone disturbances. Only a growth hormone deficiency is very rare. [3]

Written informed patient consent for publication has been obtained.