Correction and clarification regarding AFX and pleomorphic dermal sarcoma

In the November edition of the JCP, my views regarding atypical fibroxanthoma (AFX) were presented1. Since the publication of that essay, I have corresponded with Dr. Christopher Fletcher, who coined the term pleomorphic dermal sarcoma, and this brief explication represents a summary of that correspondence. Dr. Fletcher’s view is that pleomorphic dermal sarcoma and atypical fibroxanthoma are not synonymous. Instead, he feels the designation AFX should be applied to tumors confined to the dermis that lack associated attributes such as necrosis or vascular invasion. In Dr. Fletcher’s experience, tumors interpreted as AFX by such criteria are essentially benign. Dr. Fletcher points out that there is only one convincing contemporary case of AFX with well-documented metastasis2, and preceding reports of metastatic AFX antedate rigorous modern immunostains or use flawed diagnostic criteria3. Based upon this information, Dr. Fletcher feels that a carefully diagnosed AFX has reassuring and unambiguous clinical implications for the patient and their physician. In Dr. Fletcher’s view, pleomorphic dermal sarcoma is a dermal-based lesion, morphologically similar to AFX, that invades into subcutis and in which a benign course cannot be confidently assumed. In the experience of Dr. Fletcher, the risk of metastasis from tumors classified as pleomorphic dermal sarcoma seems to be very small, despite the high grade morphology. Dr. Fletcher estimates metastatic risk at less than 5% but acknowledges that that figure is anecdotal.