Keratoacanthoma (KA) is a type of skin lesion that often causes concern due to its rapid growth and appearance. It typically originates from the hair follicles and presents as a dome-shaped tumor on the outermost layer of the skin. While generally considered a low-grade tumor, its resemblance to more aggressive skin cancers frequently leads to a need for professional evaluation.
Identifying Early Keratoacanthoma
An early keratoacanthoma typically appears as a small, round, or dome-shaped bump on the skin. These lesions often begin as flesh-colored or pinkish-red papules and grow rapidly over several weeks, usually reaching a size of 1 to 2 centimeters in diameter. The growth then develops into a firm, elevated nodule with sharply sloping borders.
A distinguishing feature is a central crater or plug, which may contain keratin, a protein found in skin and hair. This central core can give the lesion a “volcano-like” or “crateriform” appearance. Keratoacanthomas commonly appear on sun-exposed areas of the body, such as the face, neck, hands, arms, and ears.
The Nature of Keratoacanthoma
Keratoacanthoma is a skin tumor that, despite its rapid growth, is considered a benign condition. However, it shares features with squamous cell carcinoma (SCC), a more aggressive type of skin cancer. Many medical professionals classify it as a low-grade variant of SCC, sometimes called “squamous cell carcinoma, keratoacanthoma type” (SCC-KA type).
A defining characteristic is its three-phase growth cycle: rapid growth, a stationary phase, and often spontaneous regression. In the rapid growth phase, the lesion grows quickly over weeks. This is followed by a stable phase, where the lesion maintains its size for 6-8 weeks.
The final phase is regression, where the lesion gradually flattens and shrinks, often leaving a scar. This spontaneous resolution is thought to be related to the lesion’s origin from hair follicles, which naturally undergo cycles of growth and regression. Despite this potential for self-resolution, professional evaluation is recommended due to the difficulty distinguishing keratoacanthoma from more aggressive forms of SCC.
Diagnosis and Treatment Approaches
Diagnosing keratoacanthoma often begins with a thorough history and physical examination, where a medical professional assesses the lesion’s appearance and growth pattern. However, because keratoacanthoma can closely mimic squamous cell carcinoma, a definitive diagnosis typically requires a biopsy. An excisional biopsy, removing the entire lesion, is often preferred as it allows for a comprehensive microscopic examination to differentiate it from SCC.
Treatment for keratoacanthoma is recommended due to its resemblance to SCC and to prevent complications like scarring or local destruction, even though some lesions may regress on their own. Surgical excision is a common and effective, ensuring complete removal and histological confirmation. Other surgical techniques include Mohs micrographic surgery, removing layers incrementally to preserve healthy skin, and curettage and electrodesiccation, scraping the lesion and using heat to destroy remaining cells.
For smaller lesions or when surgery is not suitable, non-surgical options may be considered. These include cryotherapy (freezing with liquid nitrogen) or intralesional injections of medications like methotrexate or 5-fluorouracil. Always seek professional medical advice for any suspicious skin lesions to ensure accurate diagnosis and appropriate management.