title: Natural course of keratoacanthoma and related lesions after partial biopsy: clinical analysis of 66 lesions.
abstract: There is some confusion regarding the classification of keratoacanthoma (KA) and related lesions that have crateriform architecture. We examined the clinical courses of 66 KA lesions and related lesions after a partial biopsy to clarify the nosological concept of KA. We histopathologically classified these lesions into five types: (i) KA at various stages (53 lesions); (ii) KA-like squamous cell carcinoma (SCC) (3 lesions); (iii) KA with malignant transformation (3 lesions); (iv) infundibular SCC (5 lesions); and (v) crateriform SCC arising from solar keratosis (2 lesions). We analyzed the clinical course in each group. The regression rate of KA was 98.1% and that of KA-like SCC/KA with malignant transformation was 33.3%. No regression was observed in either infundibular SCC or crateriform SCC arising from solar keratosis. Thus, KA is a distinct entity that should be distinguished from other types of SCC with crateriform architecture based on the high frequency of regression. The regression rate of 33.3% in KA-like SCC/KA with malignant transformation indicated that KA lesions with an SCC component still have the potential for regression. However, this result also indicated that KA is biologically unstable, and some KA tend to evolve into conventional SCC with a gradual loss of the capacity for the spontaneous regression. Infundibular SCC and crateriform SCC arising from solar keratosis are fundamentally different from KA, not only according to the histopathological findings but also based on the biological properties.
authors: Department of Dermatology, Hyogo Cancer Center, Akashi, Japan.
authors: Toshihiro
authors: T
authors: Takai
authors: Noriyuki
authors: N
authors: Misago
authors: Yozo
authors: Y
authors: Murata
mesh_terms: D001706:Biopsy; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D007636:Keratoacanthoma / Q000473:pathology*; D007642:Keratosis / Q000473:pathology; D012075:Remission, Spontaneous; D012871:Skin Diseases / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology
keywords: clinical course; crateriform squamous cell carcinoma; infundibular squamous cell carcinoma; keratoacanthoma; regression