Pituitary stalk interruption syndrome: a rare cause for poor developmental growth in children

A 7-years–6-months old boy presented to the endocrinology clinic with complaints of poor weight and height gain, which was first observed by the parents when the child was 5 years old. The child was born out of a non-consanguineous marriage by caesarean section due to breech presentation. His birth weight was 2.35 kg. He had no perinatal complications like jaundice, dehydration or hypoglycaemia.

On recent examination, his weight, height and body mass index were 15.8 kg (<3rd centile), 108 cm (<3rd centile) and 13.6 kg/mm³ (10–25th centile), respectively. These indicated poor physical growth for age. However, the child was active with normal assessment for mental development. His lab investigations showed raised thyroid stimulating hormone (3.80 µIU/ml) with reduced thyroxine (FT4, 0.6 ng/ml). A growth hormone (GH) stimulation test was done which showed that the post clonidine (0, 30, 60, 90, 120 minutes – <5 mcg/l). Insulin growth factor levels were <25 ng/ml (40–255 ng/ml). This biochemical picture pointed towards the diagnosis of anterior pituitary hormone deficiency.

For further evaluation, contrast-enhanced magnetic resonance imaging MRI (CE-MRI) brain with sella protocol was done in our department, the findings of which included hypoplastic anterior pituitary gland with a maximum height of 3 mm (normal height = 5.4 ± 1.5 mm) [1] and an ectopically placed posterior pituitary bright spot at the level of the optic chiasma. The pituitary stalk was not visualized (Figure 1a and b). No other significant abnormality was seen. Based on these CE-MRI features, the radiological diagnosis of pituitary stalk interruption syndrome (PSIS) was made.

Figure 1.

(a) Sagittal and (b) coronal T1 weighted MRI image showing bright posterior pituitary spot at optic chiasma (small white arrow in a and b), and hypoplastic anterior pituitary in the sella turcica (large white arrow in a) with non-visualization of the pituitary stalk.

PSIS is characterized by the triad of an absent or hypoplastic anterior pituitary, thin or absent infundibulum and ectopic posterior pituitary. It is a rare disorder with an estimated incidence of 0.5/100, 000 births [2]. The clinical presentation varies according to the age of the patient and the severity of hormone deficiency. While neonates present with hypoglycaemia and failure to thrive, young children usually present with growth retardation. Delayed puberty is seen in adolescents. Initially, the patient may present with only GH deficiency which may eventually progress to multiple pituitary hormone deficiencies with a preserved posterior pituitary function. There are multiple associations seen with PSIS like breech delivery, neonatal hypoxemia, micropenis and cryptorchidism [3]. Brain MRI shows a range of features that includes small sella turcica, anterior pituitary hypoplasia and absence of the pituitary stalk and the presence of high signal posterior pituitary at the ectopic location, mostly at the infundibulum or at the median eminence of the hypothalamus [4,5]. Contrast-enhanced MRI is more effective than non-contrast MRI to look for the enhancement of the pituitary stalk and to look for the integrity of the hypothalamo-hypophyseal pituitary vessels [6].

With the recent advancements in radiological and biochemical investigations, diagnosis of this rare entity can be done at an early age, which can prompt the clinicians to start hormonal replacement therapies at the earliest, thus, providing the child with a better opportunity for age-appropriate wholesome growth [7].

Clinical presentation, biochemical investigations, and radiological findings in our case supported the diagnosis of PSIS. The child was started on GH and thyroxine supplementation and is maintaining well on the supplements. The child’s further treatment plan includes hormonal supplementation and close growth monitoring.

CONFLICT OF INTEREST

The authors declare that there is no conflict of interest regarding the publication of this article.

FUNDING

None.

ETHICAL APPROVAL

Ethical approval was obtained from the Ethics Committee of our institute. Informed consent for participation and publication of medical details was obtained from the parents. Confidentiality was ensured at all stages.