Coronal (image 1) and sagittal (image 2) T1-weighted images | Figure 1

CincyKidsRad

Cincinnati Children's Radiology

Coronal (image 1) and sagittal (image 2) T1-weighted images focused on the pituitary show a thickened proximal infundibulum (arrow) with increased signal and narrowing distally. Langerhans' cell histiocytosis can rarely affect the central nervous system. When the central nervous system is affected, it most commonly appears as thickening of the infundibulum. Patients may present with diabetes insipidus.

Axial (image 1), coronal (image 2), and sagittal (image 3) T1-weighted post-contrast MRI focused on the pituitary show thickening of the infundibulum (arrow) and enlargement of the pituitary (arrowhead). Langerhans cell histiocytosis rarely affects the central nervous system. When it does, patients may present with diabetes insipidus, ataxia, or hydrocephalus. Diabetes insipidus is a common manifestation when the posterior pituitary and infundibulum are infiltrated by Langerhans cells. Infundibular thickening greater than 3 mm is suggestive of involvement.

Sagittal T1-weighted MRI shows abnormal thickening of the pituitary infundibulum (arrow, image 1). There is also posteriorly inferior displacement of the posterior pituitary bright spot. This is in contradistinction to a normal-appearing infundibulum (arrow, image 2). Langerhans cell histiocytosis can affect the pituitary infundibulum and causes diabetes insipidus. On MRI, the most common findings of pituitary involvement of Langerhans cell histiocytosis includes the absence of the posterior pituitary bright spot and infundibular thickening.

Sagittal T1 image in a 3 year old girl with central diabetes insipidus shows a thickened pituitary infundibulum (red arrow) and absent T1 bright posterior pituitary (blue arrow). In children, Langerhans cell histiocytosis (LCH), as in this case, and germinoma are the primary considerations. The infundibulum is the most frequent location for intracranial LCH involvement.

Image description
Axial (image 1) and coronal T2-weighted (image 2) MRI shows confluent increased T2 signal with cord expansion (arrow) extending from T9 through the conus. Axial T2-weighted imaging of the cerebellum (image 3) demonstrates focal abnormal T2 signal (arrowhead) within the right brachium pontis.

Teaching point
Transverse myelitis is an inflammatory disorder of the spinal cord characterized by longitudinally extensive T2 hyperintensity with cord swelling. Lesions often span multiple vertebral segments and may be associated with additional inflammatory lesions elsewhere in the central nervous system, as seen in the brainstem. This distribution supports an immune-mediated process rather than compressive or vascular myelopathy.