Natural History of Keratoacanthoma: A Case of Spontaneous Regression in the Lower Eyelid

Introduction Keratoacanthoma (KA) is a low-grade, very rapidly growing and typically self-limiting epithelial tumour arising from the infundibulum of hair follicles. It often presents as a dome-shaped nodule with a central keratin plug, typically on sun-exposed skin in elderly individuals. Although histologically and clinically similar to squamous cell carcinoma (SCC), keratoacanthoma is usually benign and may regress spontaneously over weeks to months [ 1 ], [ 2 ], [ 3 ]. Risk factors include chronic UV exposure, trauma, chemical carcinogens (e.g. tar, tobacco), human papillomavirus (HPV) and immunosuppression. The differentiation from SCC is critical, as misdiagnosis can lead to under- or overtreatment. Standard treatment is surgical excision, both for diagnostic certainty and complete removal. Publication History Received: 02 November 2025 Accepted: 14 January 2026 Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 14, 70469 Stuttgart, Germany