Fibrinoid necrosis (pink bland featureless areas) is the key feature of ischemic fasciitis. The fat adjacent within and adjacent to the lesion appears infarcted.
Vascular granulation tissue with an inflammatory infiltrate common surrounds the fibrinoid degeneration.
Spindled myofibroblasts in a loosely texted stroma contain scattered enlarged cells.
These ganglion-like cells are also seen in proliferative fasciitis and proliferative myositis. The cells have enlarged nuclei with vesicular chromatin and basophilic cytoplasm.
Ischemic fasciitis, also known as atypical decubitus fibroplasia, is a variant of proliferative fasciitis. These lesions most often occur over the bony prominences (shoulder, hip, sacrum) of elderly or mobility-impaired patients and thought to be due to degenerative ischemic changes, similar to decubitus ulcers.
Histologically, there is a proliferation of spindled myofibroblasts and scattered ganglion-like cells, characterisitic of proliferative fasciitis. Central areas of fibrinoid necrosis with surrounding granulation tissue are hallmark features. Adjacent fat often appears infarcted (Fletcher).
Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 3rd Ed. Philadelphia, PA: Elsevier; 2007: 1541-2.
Folpe AL, Inwards CY. Bone and Soft Tissue Pathology: Foundations in Diagnostic Pathology Philadelphia, PA: Elsevier; 2010: 242.