[Acral myxoinflammatory fibroblastic sarcoma: a report of two cases].

Acral myxoinflammatory fibroblastic sarcoma is a rare low-grade malignant soft tissue tumor, usually observed in the extremities of middle-aged adults. We report two cases which occurred in the thumb and knee of middle-aged women. Both tumors showed a multinodular architecture, with cellular areas, occasional foci of hyalinized fibrosis, and hypocellular areas with a myxoid background. Various neoplastic cells were identified including spindled or rounded epithelioid cells and occasional bizarre giant cells, morphologically mimicking Reed-Sternberg cells or ganglion cells. Tumor cells were strongly immunoreactive for vimentin, and variably positive for CD68 and CD34. Both tumors were completely resected and patients were free of disease without any further treatment after a mean follow-up of 14 months.