Which lesion is considered precancerous and may progress to squamous cell carcinoma if untreated?

• A. Lentigo
• B. Actinic keratosis
• C. Keratoacanthoma
• D. Pyogenic granuloma

Answer: (B)

Actinic keratosis represents a sun-related change in the epidermis where atypical keratinocytes are confined to the surface layer. It appears as a rough, scaly or keratotic patch on sun-exposed areas such as the face, ears, or backs of the hands. This lesion is considered precancerous because the atypical cells have the potential to evolve into invasive squamous cell carcinoma if left untreated. The goal in management is to eradicate the lesion and prevent progression, using approaches like cryotherapy, topical agents such as 5-fluorouracil or imiquimod, or photodynamic therapy, along with strict sun protection.

Lentigo is a benign flat pigmented spot due to increased melanin and does not carry the same precancerous risk. Keratoacanthoma is a rapidly growing lesion that can resemble squamous cell carcinoma histologically but is generally considered a distinct entity and is not the classic precancerous lesion described here. Pyogenic granuloma is a vascular, bleeds-easily lesion and is not precancerous.