Ischemic fasciitis (rare plural: ischemic fasciitides) refers to a reactive pseudosarcomatous fibroblastic or myofibroblastic proliferation associated with physical constraints.
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Terminology
Terms that are no longer recommended for use include ‘pseudosarcomatous fibromatosis’ and ‘atypical decubital fibroplasia’.
Epidemiology
Mostly elderly or physically impaired patients are affected by the condition with a slight male predilection 1-4.
Diagnosis
The diagnosis of ischemic fasciitis is based on typical pathological features.
Diagnostic criteria
Diagnostic criteria of ischemic fasciitis according to the WHO classification of tumors: soft tissue and bone (5th edition) 1:
- mass-forming structure in the deep subcutaneous tissue
- zonal appearance with an avascular central component consisting of fibrinoid degeneration/necrosis and cystic changes
- a peripheral component made up of granulation tissue-like vascular proliferation
- intermingled plump fibroblasts and myofibroblasts
Clinical presentation
Usually, the lesion manifests as a painless mass that can be sometimes debilitating and associated with immobility and bedriddenness 1-6.
Pathology
Ischemic fasciitis is characterized by mass-forming lesions in the deep soft tissues with a zonal appearance 1-3.
Etiology
The cause of ischemic fasciitis includes constant pressure or repetitive trauma to the affected region 1-6.
Location
Ischemic fasciitis usually develops in the deep subcutaneous tissue over a bony prominence but can also involve the skin the skeletal muscle or tendinous tissues 1-4. The limb-girdle and the sacral region, the greater trochanter area or the shoulder are commonly affected sites, and the chest wall or back are other possible locations 1,2,6,7.
Macroscopic appearance
Grossly ischemic fasciitis might display a white to yellow fibrous appearance with central necrosis and occasionally cystic change 1.
Microscopic appearance
The main histological feature of ischemic fasciitis is a zonal resemblance 1-6,8:
- central areas of hypocellular fibrinoid necrosis or degeneration possibly associated with fat necrosis and/or pseudocystic degeneration
- granulation tissue-like vascular proliferation of thin-walled vessels and fibroblastic or myofibroblastic cells surrounding the central area
- variable mitotic activity, no atypia
- fibrin thrombi within peripheral vessels with possible fibrinoid necrosis
Immunophenotype
Immunohistochemistry stains are variably positive for smooth muscle actin, desmin, vimentin or CD34 1,2,4.
Radiographic features
Imaging features have been described as lobulated and irregular associated with surrounding soft tissue edema and reactive inflammatory changes as well as continuity with the thickened fascia 5-7.
Ultrasound
On ultrasound ischemic fasciitis has been described as a lobulated hypoechoic subcutaneous lesion with multiple hyperechoic nodules and variable vascularity on color Doppler 5,6.
CT
On CT the lesion has been reported to show irregular borders and an attenuation isodense to skeletal muscle and hyperintense to the surrounding fatty tissue with nodular contrast enhancement 6.
MRI
On MRI ischemic fasciitis has been described to show a soft tissue mass with irregular or ill-defined margins in typical locations with the intralesional fluid-like signal intensity of the ischemic and necrotic areas and surrounding edema as well as breaching of the fascia in some cases 5-7.
Signal characteristics
- T1: roughly isointense to skeletal muscle
- T2: heterogeneous high signal intensity
- STIR/PDFS: heterogeneous high signal intensity
- T1C+(Gd): marked enhancement with smaller non-enhancing areas of necrosis
Radiology report
The radiological report should include a description of the following:
- form, location and size
- tumor margins and transition zone
- relation to the muscular fascia
- relation to bone
Treatment and prognosis
Local excision can be curative 4. However, in the case of persistence of the underlying cause, there might be local recurrences 1.
History and etymology
Ischemic fasciitis was first described under the term ‘atypical decubital fibroplasia’ in 1992 by Elizabeth Ann Montgomery and her colleagues 5-8.
Differential diagnosis
Ischemic fasciitis can mimic the appearance of the following conditions 5-7:
- soft tissue sarcomas
- phlegmon or abscess
- soft tissue involvement of lymphoma