Solitary epidermolytic acanthoma: a clinical and histopathological study

Background Epidermolytic acanthoma (EA) is an uncommon cutaneous entity that typically presents as a solitary lesion, or, less commonly, as multiple or disseminated discrete lesions. It usually appears at or after middle‐age, and has been reported in various locations including the face, trunk, extremities and genitalia. Histopathologically, EA shows epidermolytic hyperkeratosis (EHK) involving either the entire thickness of the epidermis or just the granular and upper spinous layers. Objective and methods To describe the clinical and microscopic features of EA, we retrospectively reviewed all cases diagnosed as EA at the Skin Pathology Laboratory at Boston University between 1999 and 2009. Results Solitary EA is more common in men (65%) and usually presents as a hyperkeratotic papule on the trunk (45%) or extremities (25%). Histopathologically, all cases of solitary EA showed the classical features of hyperkeratosis, acanthosis and EHK. Three architectural patterns were observed on scanning magnification: papillomatous (55%), cup‐shaped (40%) and acanthotic (15%). Additional common features encountered included focal parakeratosis (85%), and a sparse to mild superficial perivascular lymphocytic infiltrate (90%). Conclusion This large case series of solitary EA reviews the clinical features of this entity and describes several new histological variants.