Case of the week Details

• A. A well defined T1 isointense, T2 hyperintense lesion with internal T1/T2 hypointense foci (Phleboliths) in the left infraorbital region.
• B. No features of diffusion restriction in DWI/ ADC images.
• C. STIR sequences showing similar signal intensity tubular foci superficial to left temporalis and masseter muscles with a T2 hyperintense tubular structure connecting these foci to the lesion in the infraorbital region.
• D. Contrast enhanced and MR  angiographic images  reveals homogeneous contrast enhancement and the lesion draining into left facial vein which in turn draining into internal jugular vein.  
• E. No  features of arterial feeders.

RADIOLOGICAL DIAGNOSIS

• A well defined T1 isointense, T2 hyperintense lesion with internal T1/T2 hypointense foci (Phleboliths) in the left infraorbital region.
• The lesion shows contrast enhancement. No features of diffusion restriction.
• A prominent vessels noted draining the lesion into left facial vein.
• No dilated or prominent arterial feeders.
• Few similar T2 hyperintense  tubular foci (vascular loops) noted superficial to left temporalis and masseter muscles.
• There is vascular channel noted connecting these foci to  lesion in the infraorbital region.
• No features of communication into cerebral venous plexus. No cavernous sinus thrombosis.

 Imaging features suggestive of low flow venous malformation in left infraorbital region with drainage into left facial vein and few similar intercommunicating venous malformations superficial to left temporalis and masseter muscle.

DISCUSSION

• Venous  malformations  (VMs)  are  congenital  endothelial  malformations that result from errors in vascular morphogenesis.
• Composed of vascular channels sometimes containing  intraluminal  thrombus,  are  lined  by  thin  endothelium.
• It is subtype of low flow vascular malformations.
• They are usually present at birth but are not always apparent and grow in proportion to the child's growth until puberty.

Clinical presentation

• Located superficially within the head and neck (40%), trunk (20%), or limbs (40%)  and can also be found in the viscera
• Presenting  complaints include cosmetic, swelling from dependent stasis,  pain  from  localized  thrombosis,  or  limitation of activities  and even altered limb growth
• Usually presents as nonpulsatile, compressible,  discrete  soft-tissue  mass  that  causes  no  alteration in skin temperature, thrill, or bruit
• Increase  in  size and coloration during a Valsalva maneuver,  with  dependent  positioning,  and  sometimes with the application of a tourniquet
• If the skin is involved, a blue-purple hue or superficial veins can be seen.
• Sudden enlargement  can happen after trauma, intralesional thrombosis, puberty, pregnancy, and oral contraceptive intake.  
• Elevated level of d-dimers can be seen secondary to thrombosis.  
• It has a variable appearance at presentation ranging from solitary to multiple,  small circumscribed to extensive  infiltrative lesion crossing multiple tissue planes.
• Three   main   venographic   patterns—cavitary,   spongiform,   and   dysmorphic
• Dubois et al. and Puig et al. further  subdivided  these  patterns  into  the  following four types based on patterns of venous drainage
  • A- type I,isolated malformations without venous drainage;
  • B- type II, malformations that drain into normal veins;
  • C- type III, malformations that drain into dysplastic veins
  • D- type IV, malformations consisting primarily of venous ectasia

US:

• Ultrasound with colour Doppler is the first line imaging to diagnose low flow venous malformation.  
• Superficial venous malformations are compressible with heterogeneous echotexture (98%) and can be hypoechoic (82% ), hyperechoic (10%) or isoechoic (8% ).  
• Calcified phleboliths are seen only in 16% of the cases.  
• Tubular anechoic structures  indicative of vascular channels are seen in 4% of cases.  
• On colour Doppler monophasic flow typical for venous  channels.  
• About 16% of the cases very low flow below the detectable limits or thrombosis can cause a diagnostic confusion.

MR:

• Hypointense to isointense on T1
• Intralesional fat or thrombi appears hyperintense on T1, and  phleboliths appears scattered punctate  T1 low-signal intensity.
• T2- markedly hyperintense, Areas of low signal  represents thrombosis or phleboliths
• Fat saturation  sequences useful for determining lesion extent
• Gradient-echo  sequences  demonstrates hemosiderin and calcification
• May have fluid-fluid levels  representing layering hemorrhage
• Circulatory portions of VMs have a wide range of contrast enhancement - homogeneous to heterogeneous, faint to vivid, and rapid to delayed

Diagnostic difficulties

Intravascular papillary endothelial hyperplasia:

•  Venous malformations are prone to stasis because of the low flow which leads to clot formation.  
• This intraluminal clot well  late to formation of exuberant intralesional intraluminal capillary ingrowth, also known as intravascular papillary endothelial hyperplasia or Masson tumor  
• On imaging  these will have variation in proportions of internal solid components and septa and low-flow vascular channels result in variable amounts of vascular flow at Doppler imaging and no reliable intensity, homogeneity, or contrast-enhancement  which  can be confused with neoplasms

Purely intramuscular vascular malformations

•  Purely intramuscular vascular malformations  will have late presentation  because of the  decreased intralesional venous stasis secondary to muscle contraction.
• Increased risk of local intravascular coagulation and thrombosis  leads to higher morbidity
• Higher rate of pain as the presenting symptom and cause greater limitation of physical activity which can be confused clinically with soft-tissue neoplasms
• Well defined, oval, or round and often are adherent to neurovascular bundles  will mimic peripheral nerve sheath tumors and soft-tissue sarcomas  
• Few intramuscular vascular malformations  have higher rates of calcification  then their  non-intramuscular counterparts.

Reference
Low-Flow Vascular Malformation Pitfalls: From Clinical Examination to Practical Imaging Evaluation- Brandon Olivieri, et al- AJR article

Dr Harsha Chadaga
Senior Consultant and Head of Radiology
Manipal Hospital, Yeshwanthpur Bengaluru

Dr. Dhinesh kumar T
Radiology resident
Manipal hospital, Yeshwanthpur, Bengaluru.