Keratoacanthoma and Other Types of Squamous Cell Carcinoma with Crateriform Architecture: Classification and Identification

The study aimed to clarify the classification and terminology of keratoacanthoma (KA) and other squamous cell carcinoma (SCC) types with crateriform architecture by evaluating 41 nodular SCC lesions. These lesions were categorized into six types, including KA, KA-like SCC, KA with malignant transformation, infundibular SCC, crateriform SCC from actinic keratosis, and crateriform Bowen's disease. The study suggested that KA, KA-like SCC, KA with malignant transformation, and infundibular SCC are related to hair follicles, while crateriform SCC from actinic keratosis and crateriform Bowen's disease are not. The findings aimed to assist physicians in making accurate differential diagnoses and to standardize the terminology for KA and related neoplasms.