A clinicohistopathologic study of a lesion resembling keratoacanthoma

Abstract

Background: Keratoacanthoma (KA) can be clinically differentiated with ease from other dermatoses. However, the differential diagnosis of KA can sometimes be difficult, and some cases clinically suggest that the results of skin biopsies of lesions thought to be KA indicate other diseases. Objective: The purpose of this study is to examine the diagnostic yield in submitting clinically diagnosed KA that showed solitary symmetric, firm, erythematous, or skin-colored nodules. Methods: We retrospectively reviewed the clinical records of 54 patients with a clinical diagnosis or differential diagnosis of KA who received biopsies and visited the department of dermatology from January 2004 to December 2013. We compared clinical and histopathologic diagnoses and analyzed the rate of concurrence. In addition, clinical features, including age, sex, location, and duration were investigated. Results: Of the patients, 40.7% were clinically diagnosed with KA, but the results of the histopathology tests indicated other diseases. The mean age of the patients with KA was 72.8 years, and the ratio of men to women was 1 : 0.92. Of the new patients, 0.07% had KA, and most of the lesion sites (84.0%) were caused by sun exposure. Other diseases that are more common in patients with KA are squamous cell carcinoma (55.2%), basal cell carcinoma (20.7%), seborrheic keratosis (6.9%), verruca vulgaris (6.9%), pyogenic granuloma (3.4%), clear cell acanthoma (3.4%), and Bowen)s disease (3.4%). Conclusion: Skin lesions thought to be KA need more examinations, and skin biopsies of appearances of clinically atypical lesions that cannot completely exclude the possibility of precancerous or malignant lesions are strongly recommended.