title: Cases with a spontaneous regression of an infiltrating non-crateriform keratoacanthoma and squamous cell carcinoma with a keratoacanthoma-like component.
abstract: We herein report the natural course of an early/proliferative stage keratoacanthoma (KA) with infiltrating islands of cytological malignancy (case 1) and a squamous cell carcinoma (SCC) with a KA-like component (case 2), which were observed until their complete regression. The presented case 1 suggests that one of the histopathological forms of KA includes this unusual, infiltrating, non-crateriform architecture, and also indicates the possibility of complete remission in the KA associated with infiltrating islands of cytological malignancy. In the presented case 2, the peripherally-associated KA-like focus was histopathologically considered to be either a remnant of KA focus or verrucous keratosis (hyperplasia). Therefore, the complete spontaneous regression of case 2 suggests that SCC arising in KA still has the potential of spontaneous regression, or that an extremely rare event, namely, the spontaneous regression of (traditional) SCC occurred in the present case.
authors.affiliation: Division of Dermatology, Department of Internal Medicine, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Misago
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Takai
authors.forename: Yozo
authors.initials: Y
authors.lastname: Murata
authors.forename: Kotaro
authors.initials: K
authors.lastname: Nagase
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Narisawa
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000150:complications / Q000473:pathology*; D005260:Female; D006801:Humans; D007636:Keratoacanthoma / Q000150:complications / Q000473:pathology*; D007642:Keratosis / Q000150:complications / Q000473:pathology; D008047:Lip Diseases / Q000150:complications / Q000473:pathology; D008048:Lip Neoplasms / Q000150:complications / Q000473:pathology; D009365:Neoplasm Regression, Spontaneous / Q000473:pathology*; D012871:Skin Diseases / Q000150:complications / Q000473:pathology*; D012878:Skin Neoplasms / Q000150:complications / Q000473:pathology*
keywords: cytological malignancy; keratoacanthoma; non-crateriform; regression; squamous cell carcinoma arising in keratoacanthoma