Response to ‘A clinical and biological review of keratoacanthoma’: reply from authors

We appreciate the interest of the authors in our review of keratoacanthoma (KA).1 They raise several points that were discussed in our manuscript. First, they suggest that the histopathological differentiation from KA and well-differentiated squamous cell carcinoma (SCC) is not as problematic as reviewed; however, they qualify that an "adequate specimen is required" and "partial biopsies are not reliable." This is a key point we discussed, as a portion of biopsies may be too small to identify important architectural features or may be unrepresentative of the tumor, which limits the ability of the pathologist to distinguish between KA and SCC2-4 , and typically leads to an overcall of SCC to avoid a missed malignancy. Indeed, most experienced dermatopathologists can accurately discriminate between KA and SCC when an ample biopsy representative of the tumor is obtained. Second, they question the practicality of using the stereotypical triphasic evolution pattern of KA to aid in diagnosis and state that "patient history is likely to be unreliable."