Pre-Cancerous Skin Lesions

Actinic Keratosis

• This is a precancerous epidermal lesion caused by excessive exposure to sunlight (UV radiation). It can easily lead to an invasive squamous cell carcinoma but could also resolve spontaneously. Clincically, it presents as a rough, scaling plaque or roughened nodule (lecture). Dr. Schwartz also mentioned that it is better palpated than visualized.

• Actinic Keratoses, thermal keratoses, chronic radiation keratoses
• Bowenoid arsenical keratoses, hydrocarbon (tar) keratoses ß chemical induced!
• Actinic chelitis (an actinic keratosis on the lip), oral erythroplakia (can progress to a dangerous oral cell carcinoma- things on mucous membranes metastasize rapidly), and erythoplasia of Queyrat (penis).
• Some of these were illustrated in slides on p. 58 of the notes—most notably the precancerous lesions caused by chronic exposure to fire.

Xeroderma Pigmentosum

• This disease is often referred to as a model disease of premature cutaneous aging and is due to defective DNA repair. The key thing to remember is that various skin pathologies are manifested very early on in life (as seen in the slide of an 8yr old girl with a keratoacanthoma on her lip). Patients affected by Xeroderma Pigmentosum get actinic keratoses, squamous and basal cell carcinomas, keratoacanthomas, and melanomas. Median age for these skin lesions in an Xeroderma Pigmentosum patient? 8 years old.

Keratoacanthoma

• This lesion is very common and is seen on the elderly on sun exposed surfaces. It is very similar to squamous cell carcinoma; however, it is a benign neoplasm that regresses without therapy (pseudomalignancy). Another thing to remember is that it enlarges alarmingly in the first stage…

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