Acral myxoinflammatory fibroblastic sarcomas: are they all low-grade neoplasms?

Acral myxoinflammatory fibroblastic sarcoma (AMIFS) is a low-grade sarcoma that presents mostly in distal extremities of middle-aged patients. The clinicopathologic features, immunohistochemical profile and follow-up data of five cases (three men and two women; age 39-65 years) are presented. The tumors presented as a slow-growing, poorly circumscribed, subcutaneous masses in the hands (three), foot (one) and calf (one), with dermal involvement in two cases. They had myxoid and hyaline stroma with dense acute and chronic inflammation. Spindle cells, large bizarre ganglion-like cells and multivacuolated cells were seen. Variable reactivity in lesional cells were noted for vimentin, Alpha-1-antitrypsin (A1AT), factor XIIIa, CD68, CD95, CD117, Alpha-1-antichymotrypsin (A1ACT), CD34, AE1/3, S-100 protein, EBER, CD63 and CD15. MIB-1 showed 5-30% nuclear labeling. They were negative for cytokeratin AE1/3, smooth muscle actin, CD30, ALK-1, EMA, desmin, CMV, HMB-45 and Melan-A. Follow up ranged from 2 weeks to 95 months (mean 54). One patient was lost to follow up; three underwent excision and one patient had below the knee amputation. Two patients developed metastases (one died of disease), and two patients are alive without evidence of disease. AMIFS are rare tumors that may involve joints and tendons leading to clinical diagnosis of ganglion cyst or tenosynovitis.