Tumefactive demyelinating lesion

A tumefactive demyelinating lesion (TDL) is a solitary lesion greater than 2 cm that mimics a neoplasm on imaging ³. 

Clinical presentation

Patients present with symptoms atypical for multiple sclerosis : focal neurologic deficits, seizures, and / or aphasia ^5. Most do not progress to multiple sclerosis ⁶.

Radiographic features

MRI Brain

The lesions tend to be large but with relatively little mass effect or surrounding oedema. Centrally located dilated veins have also been observed within these lesions ¹. 

• T1 C+ (Gd) : about half of tumefactive demyelinating lesions demonstrate contrast enhancement ² ; the enhancement pattern is usually in the form on an open ring and the incomplete portion of the ring is on the gray matter side of the lesion ⁴. 
• perfusion imaging : helps differentiate tumefactive demyelinating lesions from the main differential considerations : high-grade gliomas and lymphomas ; mean relative cerebral blood volume within tumefactive demyelinating lesions have been found to be substantially less than in high-grade gliomas and lymphomas ¹.
• diffusion imaging (DWI) : 
  • can be less helpful in differentiating tumefactive demyelinating lesions from tumours, as necrotic neoplasms may display a similar increase in apparent diffusion coefficient (ADC) 
  • however, diffusion imaging can help differentiate ring-enhancing tumefactive demyelinating lesions from cerebral abscesses
  • while the former show mildly increased ADC, the latter demonstrate restricted diffusion. ³ 

Differential diagnosis

General imaging differential considerations include

• glioma
• CNS lymphoma
• cerebral inflective process : cerebritis