Two cases of Atypical fibroxanthoma are reported. A 75-year-old man had noticed a small hemorrhagic nodule on the left temple for about 6 months. It had enlarged rapidly over a period of a few months. A 68-year-old white man had noticed a reddish nodule, which had rapidly enlarged, on the top of his bald head. The histological examination of the resected tissues from both patients showed poorly margined tumoral lesions in the dermis and partly subcutaneous tissue. These tumors consisted mainly of atypical fibroblasts or histiocyte-like spindle cells, with scattered mitosis. Immunohistochemical findings revealed that tumor cells were positive for vimentin, CD10, and focally for CD99, and negative for cytokeratins, S100 protein, desmin and CD34. We diagnosed these cases as atypical fibroxanthoma based upon these findings. Both patients showed no findings of recurrence or metastasis. Although atypical fibroxanthoma is often difficult to distinguish histologically from other malignant tumors, immunohistochemical staining can be a helpful tool in the differential diagnosis.
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