Makindo Medical Notes

📊 Epidemiology

• 👵 More common in individuals over 50 years.
• 👶 Rare in individuals under 20 years.
• ☀️ Typically seen in fair-skinned individuals with a history of chronic sun exposure.

🧾 Differential Diagnosis

• 🚨 Always treat as Squamous Cell Carcinoma (SCC) until proven otherwise, given its identical appearance and risk profile.
• 🌞 Hypertrophic solar keratosis (actinic keratosis).
• 🦠 Verruca vulgaris (common warts).
• 📉 Rarely, Basal Cell Carcinoma (BCC) can mimic keratoacanthoma.

🔬 Pathophysiology

• Keratoacanthoma is an epithelial neoplasm arising from the epidermis.
• Composed of atypical keratinocytes forming a dome-shaped lesion with a keratin core.
• Considered a low-grade variant of SCC → may spontaneously regress.
• ⚡ Grows rapidly (weeks) → may regress in months, often leaving a scar.

🧪 Etiology & Risk Factors

• 🦠 HPV infection: Especially HPV types 5 & 8.
• ☀️ UV radiation exposure: Major risk factor in fair-skinned individuals.
• 🛢️ Chemical carcinogens: Tar, mineral oils, hydrocarbons.
• 🧬 Genetic syndromes: Rare association with Muir–Torre syndrome.
• 💊 Immunosuppression: Organ transplant recipients & chemotherapy patients at higher risk.

🩺 Clinical Presentation

• Rapidly growing, dome-shaped nodule with a central keratin plug → often described as an “erupting volcano”. 🌋
• Color: erythematous to skin-colored.
• Site: sun-exposed areas (face, neck, forearms, hands).
• Course: rapid growth over weeks, then possible spontaneous regression with scarring.
• 🚨 Clinically indistinguishable from SCC → always biopsy or excise.

🛠️ Management

• ✂️ Surgical excision: Gold standard to exclude SCC and ensure cure.
• 🔥 Curettage and cautery: Suitable for small lesions.
• ❄️ Cryotherapy: Useful in selected superficial lesions.
• 👀 Observation: Rarely considered if spontaneous regression is evident, but ⚠️ risky since SCC cannot be excluded clinically.
• 💊 Topical therapies: Imiquimod or 5-fluorouracil for superficial/recurrent lesions in select cases.

📌 Clinical Pearls

• 🚨 Treat as SCC until histology confirms keratoacanthoma.
• ⚡ Rapid growth → helps distinguish from many benign lesions.
• 📉 Spontaneous regression possible, but histology is essential to avoid missing SCC.
• 🩺 Immunosuppressed patients → higher risk of multiple or aggressive lesions.

✅ Conclusion

Keratoacanthoma is a rapidly growing, crateriform skin lesion often mistaken for squamous cell carcinoma. While many regress spontaneously, the potential overlap with invasive SCC means biopsy and often surgical excision are mandatory. Awareness of risk factors (UV, HPV, immunosuppression) and classic appearance (“volcano with keratin plug”) supports early recognition and safe management.