CASE 18750 Published on 24.10.2024

Partial ectopic posterior pituitary in a child with short stature

Section

Paediatric radiology

Case Type

Clinical Case

Authors

José Flávio de Oliveira Neto, Ana Beatriz Venancio de Paula Bezerra, Antonio Cavalcanti Neto, Soraya Silveira Monteiro

Department of Diagnostic Imaging, Federal University of São Paulo Unifesp, São Paulo, Brazil

Hospital São Paulo / Unifesp University Hospital, São Paulo, Brazil

Patient

12 years, male

Categories
Area of Interest Neuroradiology brain, Paediatric ; Imaging Technique MR
Clinical History

A 12-year-old male presented with isolated short stature (130 cm; 3rd percentile). Thus, an initial workup for growth disorders was performed, revealing an altered bone age estimated to be of 10 years old (-2.85 SD). Following these findings, both a hormone profile and brain imaging were requested.

Imaging Findings

For this study, a 3.0 T magnetic resonance imaging of the sella turcica was performed in two phases, one with contrast and one without. The pre-contrast sagittal image revealed two hyperintense structures on T1: one in the posterior portion of the sellar region (consistent with the topography of the neurohypophysis) and another in the suprasellar region adjacent to the optic chiasm. The pituitary stalk was present and continuous, albeit thin (< 0.1 mm), and the anterior lobe (adenohypophysis) had a normal signal although reduced in size, measuring 4.5 mm.

Discussion

In addition to the imaging findings, laboratory tests suggested reduced growth hormone (GH) secretion, according to the following results:

  • Clonidine stimulation test: 0 minutes: 5.14 ; 60 minutes: 0.74 ; 90 minutes: 0.81 ; 120 minutes: 0.54.
  • Insulin stimulation test: 0 minutes: 1.11 ; 30 minutes: 1.84 ; 60 minutes: 1.42 ; 90 minutes: 7.63 ; 120 minutes: 1.80
  • IGF-1: 83.2.

In this context, the findings suggest pituitary stalk interruption syndrome (PSIS) due to partially ectopic posterior pituitary gland.

Background

Partially ectopic neurohypophysis is a new clinical entity first described in 2019 by Marina Ybarra [1]. She identified a partial defect of the neurohypophysis, which presents as two bright spots on the midline: one in the suprasellar region and another in the sella.

Adamantinomatous craniopharyngioma (ACP) and intracranial teratoma can be ruled out due to the lack of mass effect symptoms, as well as the peripheral calcification characteristic of ACP and the determining presence of fat and cystic areas in teratomas [2,3]. Another possible diagnosis is intracranial lipoma; however, this is a non-characteristic location and they are usually asymptomatic and could not account for the growth delay presented by this patient [4].

PSIS, on the other hand, is a rare congenital anomaly of the pituitary gland first described by Fujisawa [1] in patients with pituitary dysmorphism. It is characterised by an ectopic posterior lobe and abnormalities of the pituitary stalk [5–7].

Imaging Perspective

The MRI has become the imaging modality of choice for evaluating endocrine disorders of the hypothalamicpituitary axis, leading to a better characterisation of anatomical abnormalities in this region [5,10]. The posterior pituitary is observed as a bright signal, posterior to the adenohypophysis, on T1-weighted MRI sequences [5]. The identification of a hyperintense signal in the posterior sella turcica can be considered a marker of the functional integrity of the neurohypophysis [12].

PSIS is radiologically characterised by the following triad: a thin (< 1 mm) or interrupted pituitary stalk, an ectopic neurohypophysis and adenohypophysis hypoplasia or aplasia [3–5]. Its prevalence is of 0.5:1,000,000 births [4,5]. PSIS can be associated with various endocrine disorders, ranging from isolated growth hormone deficiency to multiple pituitary hormones deficiency [7,9–11].

Outcome

Given this clinical picture, the team decided to start GH therapy and monitor growth every 3 months for 2 years, resulting in a satisfactory growth curve.

Take Home Message

It can be concluded that PSIS consists of the triad of a thin or interrupted pituitary stalk, ectopic neurohypophysis and adenohypophysis hypoplasia or aplasia. This condition can be associated with reduced GH secretion and, consequently, growth disorders.

Although clinical signs suggest the condition during the first decade of life, the diagnosis of PSIS is generally delayed, typically made when the patient already exhibits short stature, reduced growth velocity, or delayed bone age [13].

Differential Diagnosis List
Ectopic posterior pituitary gland
Craniopharyngioma
Lipoma
Teratoma
Final Diagnosis
Ectopic posterior pituitary gland
Case information
URL: https://eurorad.org/case/18750
DOI: 10.35100/eurorad/case.18750
ISSN: 1563-4086
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