Table of Contents
Overview – Keratoacanthoma
Keratoacanthoma (KA) is a low-grade, rapidly growing skin lesion that arises from the hair follicle epithelium. It is most commonly seen in older adults with fair skin and a history of chronic sun exposure. Although histologically similar to squamous cell carcinoma (SCC), KA often demonstrates spontaneous regression. Nonetheless, it is usually excised due to difficulty in distinguishing it from SCC clinically and histologically.
Definition
Keratoacanthoma is a benign but potentially locally aggressive epithelial tumour originating from hair follicle cells, characterised by rapid growth and a central keratin plug.
Aetiology
- Chronic sun exposure (UV radiation)
- Fair skin phototypes (Fitzpatrick I–II)
- Advanced age
- Genetic predisposition in some familial syndromes
- Immunosuppression (e.g. organ transplant patients)
Pathophysiology
- Proliferation of follicular epithelium, likely triggered by UV-induced DNA damage
→ Rapid tumour growth
→ Spontaneous regression in some cases - Shares molecular and histological features with squamous cell carcinoma
→ Often treated as a potential malignancy
Clinical Features
- Typically presents in sun-exposed areas (face, forearms, hands)
- Firm, dome-shaped nodule
- Central keratin-filled crater (“hard keratin core”)
- Lesion appears suddenly and grows rapidly over weeks
- Can be mildly painful or irritating
- Often reaches a size of 1–2 cm within 6–8 weeks
- May regress over several months but commonly excised due to diagnostic uncertainty
Management
- Surgical Excision (definitive management and diagnostic confirmation)
→ Histopathological examination to rule out SCC - Cryotherapy for small lesions (<0.5 cm) or in non-surgical candidates
- Close monitoring if excision is deferred (less common approach)
- Radiation or topical therapy is generally not indicated
Summary – Keratoacanthoma
Keratoacanthoma is a rapidly growing, dome-shaped skin lesion with a central keratin plug, typically arising in sun-damaged skin of older adults. While often benign and self-limiting, it is usually managed with surgical excision due to its resemblance to squamous cell carcinoma. For a broader context, see our Skin & Dermatology Overview page.