Tumefactive demyelinating lesion

Tumefactive demyelinating lesion (TDL), also sometimes referred to as monofocal acute inflammatory demyelination (MAID), is a locally aggressive form of demyelination, usually manifesting as a solitary lesion (or sometimes a couple of lesions) greater than 2 cm that may mimic a neoplasm on imaging. 

On imaging they usually present with relatively little mass effect or surrounding oedema, contrast enhancement in an open-ring pattern, high ADC values, and low relative cerebral blood volume (rCBV).

As is the case with multiple sclerosis, and other demyelinating diseases, tumefactive demyelination is most frequently encountered in women, usually young middle age (average onset at 37 years of age) 3.

Unlike acute disseminated encephalomyelitis (ADEM), tumefactive demyelinating lesions are usually not post infective. Additionally, although patients with multiple sclerosis can develop large tumefactive demyelinating plaques (which have very similar appearances - see tumefactive multiple sclerosis), patients who present with a solitary tumefactive demyelinating lesion infrequently go on to develop multiple sclerosis (MS) 3

Patients present with symptoms atypical for multiple sclerosis such as focal neurologic deficits, seizures, and/or aphasia 5. Most do not progress to multiple sclerosis 6. In some instances patients can deteriorate rapidly and succumb to the the illness (e.g. acute malignant Marbug variant of MS).

CT

Tumefactive demyelinating lesions appears as a large hypoattenuating lesion with ill-defined ring enhancement, central necrosis, perilesional oedema and minimal mass effect 7.

MRI

Tumefactive demyelinating 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 1,9

  • 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
  • MR spectroscopy
    • elevation of choline 9
    • elevation of lactate 9

General imaging differential considerations include

  • high grade glioma (e.g. GBM)
    • enhancement is usually a complete ring around central necrosis
    • prominent surrounding vasogenic oedema 
    • may have non-enhancing tumour
  • CNS lymphoma
    • vivid usually solid enhancement, without central non-enhancement (except sometimes in immunocompromised individuals)
  • cerebral infective process: cerebritis or cerebral abscess
    • restricted diffusion prominent in central liquid component
  • often there is no evidence of established multiple sclerosis, and many patients do not go onto to develop MS
  • tumefactive demyelination is not necessarily benign, and patients can have a fulminant course ending in demise (e.g. Marburg variant of MS
  • lesions are centred on white matter and involve subcortical U-fibers
  • less mass effect than expected for size
  • incomplete leading edge enhancement is characteristic
  • CBV is lower than in tumours

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Article information

rID: 2225
Section: Pathology
Synonyms or Alternate Spellings:
  • Tumefactive demyelination
  • Tumefactive demyelinating lesions
  • Tumefactive demyelinating lesion (TDL)
  • Monofocal acute inflammatory demyelination
  • Monofocal acute inflammatory demyelination (MAID)
  • MAID
  • Inflammatory Demyelinating Pseudotumour

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