Actinic keratosis and squamous cell carcinoma

Actinic keratosis involves abnormal keratinocytes near the skin surface after cumulative ultraviolet damage. Squamous cell carcinoma occurs when malignant keratinocytes grow beyond that limited pattern and can invade nearby tissue. The shared cell type and sun-damage pathway explain the connection, but the labels describe different stages of disease.

Texture and appearance overlap, particularly when an actinic keratosis becomes thick or tender. A dermatologist uses the history and examination to judge the lesion; a biopsy provides tissue for diagnosis when clinical features cannot settle the distinction.

Schedule an assessment rather than trying to identify the stage at home. Record whether the area has enlarged, hardened, bled or become painful, and mention previous treatment at the same site. Do not apply a leftover actinic keratosis medicine to a newly suspicious lump before it has been examined, because inflammation can obscure its features.

If actinic keratosis is confirmed, management may address an individual spot or a wider field of altered skin. If biopsy identifies squamous cell carcinoma, the clinician will explain removal and follow-up according to its site, size, depth and tissue findings.

Seek prompt review when a rough patch develops a firm raised component, accelerates in growth, becomes persistently painful, bleeds with minimal contact or creates a non-healing ulcer. A lesion returning soon after apparently successful treatment also deserves reassessment. Urgency follows these concerning changes; it should not be based on an assumption that every actinic keratosis has become carcinoma.

Ask which findings favour actinic keratosis, which raise concern for invasion, and whether a biopsy is needed before treatment. If tissue is sampled, ask how and when results will be communicated, what wound care is required, and what the next step would be for each possible diagnosis.