Vascular malformations

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Vascular malformations come in different flavours.

Types:[1]

  1. Arteriovenous malformation.
    • Most important clinically - highest risk of bleeding.
  2. Varix.
    • One large (dilated) vein.
  3. Venous angioma.
    • Many small veins.
  4. Caverous malformation.
    • Vessels are back-to-back (no intervening parenchyma).

Also see: Sturge-Weber syndrome.

Arteriovenous malformation

General

  • High risk for bleeding vis-a-vis other vascular malformations.

Gross

Features:[1]

  • Classically wedge-shaped - with base toward superficial aspect and apex toward deep aspect (like pulmonary infarcts).
  • Usually middle cerebral artery distribution.

Microscopic

Features:

  • Large vessels with eccentric wall thickening.
    • "Large" = ~ 0.5 mm (0.25-1.0 mm).
      • 0.25 mm = ~ 31 RBC diameters across.

Image: Cerebral AVM (WC).

Notes:

  • There is usually one feeding artery.
  • Arteries have a well-defined internal elastic lamina and an external elastic lamina (best seen on elastic trichrome).
    • Veins do not have an external elastic lamina and have a poorly developed/thin internal elastic lamina.

Cavernous angioma

General

  • Usually diagnosed by radiology.

Microscopic

Features:

  • Vessels back-to-back/little intervening parenchyma.
    • Muscle is absent in the vessel walls - key feature.[2]

References

  1. 1.0 1.1 Prayson RA, Kleinschmidt-DeMasters BK (November 2006). "An algorithmic approach to the brain biopsy--part II". Arch. Pathol. Lab. Med. 130 (11): 1639–48. PMID 17076525.
  2. MUN. 23 November 2010.