Acral myxoinflammatory fibroblastic sarcoma: a report of five cases and review of the literature.

Five cases of acral myxoinflammatory fibroblastic sarcoma that occurred in the distal extremities within the subcutaneous tissue are described. In one case, recurrence and metastases were recognized rather rapidly, only 3 months after the first excision. There have been no reports of early recurrence or metastases, especially the latter. The predominant type of constituent cells, cellularity of the neoplastic cells and density of inflammatory cells varied microscopically among cases. However, characteristic ganglion-like cells, Reed-Sternberg-like cells, round mononuclear cells and myxoid stroma, sometimes only seen focally, were found in all cases. Positive immunoreaction for vimentin was present in all cases. There was no correlation between positivity of MIB-1 or p53 for the primary tumor and presence of recurrence or metastases. In conclusion, we should be more cautious about the possibility of recurrence or metastases in earlier phases of acral myxoinflammatory fibroblastic sarcoma. Identification of the atypical bizarre fibroblastic component as the manifestation of the malignant nature of this lesion is vital to correct diagnosis, and it is important to attend to the myxoid and hyalinized zones, the inflammatory infiltrate, the presence of ganglion-like cells and acral location as features of acral myxoinflammatory fibroblastic sarcoma.