Ischemic fasciitis: analysis of 44 cases indicating an inconsistent association with immobility or debilitation.

Ischemic fasciitis is a rare pseudosarcomatous proliferation of atypical fibroblasts described to be located over bony protuberances and said to develop most often in immobile elderly or debilitated patients. We report the clinicopathologic features of 44 cases of this pseudosarcomatous reactive fibroblastic/myofibroblastic proliferation. There were 15 female and 29 male patients between 23 and 96 years of age (median: 74 y). Tumor size, known in 34 cases, ranged from 1.3 to 10 cm (median: 4.7 cm). The lesions developed mostly in the deep subcutis (27 cases) and infiltration of deep dermis, muscle, and tendinous tissue was sometimes observed. In 3 cases, the lesion developed within skeletal muscle. In 33 cases (76.7%), the tumor was located around the limb girdles and sacral region; 5 tumors each (23.3%) occurred on the chest wall and the back. A history of physical debilitation could be confirmed in only 7 patients. Nine patients had a history of chronic or malignant diseases and 4 patients had a history of local trauma. The histologic hallmark of this reactive proliferation is a zonal appearance with central fibrinoid degeneration/necrosis and cystic changes surrounded by a granulation tissuelike vascular component, mixed with plump amphophilic reactive fibroblasts and myofibroblasts morphologically similar to proliferative fasciitis. Immunohistochemistry was performed in 18 cases, showing focal positivity for smooth muscle actin (37.5%), desmin (40%), or both (14.3%), underlining the fibroblastic/myofibroblastic nature of these lesions, whereas S-100 and Pan-keratin were consistently negative. Follow-up data were available in 13 cases and ranged between 6 and 72 months (median: 31.3 mo); local recurrence was observed in 1 case in which the patient was physically debilitated. Recognition of this distinct entity as a reactive process, by no means always associated with debilitation, is essential to avoid confusion with soft tissue sarcomas.