PDT for Precancerous Spots on the Hands and Forearms

Rough, scaly spots on the backs of the hands or forearms are easy to dismiss as dryness or normal aging. In some cases, however, they may be actinic keratoses, which are precancerous growths associated with accumulated ultraviolet exposure. Because these areas receive years of incidental sunlight while driving, walking, gardening, or spending time outdoors, they can develop both visible spots and less obvious sun-damaged cells.

Photodynamic therapy, commonly called PDT, is one option a dermatologist may consider for treating multiple actinic keratoses across a broader area. It combines a light-sensitive medication with a controlled light source to target abnormal surface cells. Whether it is appropriate depends on the appearance, thickness, location, and number of spots, as well as your medical history.

Quick answer

• PDT may be considered when several actinic keratoses are present across sun-damaged skin.
• The treatment involves applying a photosensitizing medication and later activating it with a specific light source.
• Redness, tenderness, swelling, crusting, or peeling can occur as the treated area heals.
• Careful protection from sunlight and bright visible light is especially important immediately after treatment.
• A dermatologist should evaluate suspicious, thick, tender, bleeding, or rapidly changing spots before treatment.

What are precancerous spots on the hands and forearms?

Actinic keratoses are rough or scaly growths that develop after repeated ultraviolet exposure. They often occur on areas that receive frequent sunlight, including the face, scalp, ears, backs of the hands, and forearms. A spot may look pink, red, tan, brown, or skin-colored. Some are easier to feel than to see and may have a gritty or sandpaper-like texture.

Although many actinic keratoses remain superficial, some can progress to squamous cell carcinoma. It is not possible to identify that risk reliably by appearance alone, so a dermatologist may recommend treatment, monitoring, or a biopsy depending on the clinical findings.

How PDT works

PDT is generally performed in stages. First, the treatment area is cleaned and prepared. A clinician may gently remove excess scale so the medication can reach the intended tissue more evenly. A photosensitizing medication is then applied to the skin and allowed to remain for a prescribed incubation period.

The area is later exposed to a controlled light source. The light activates the medication in the targeted cells, producing a localized reaction that damages abnormal tissue. The specific medication, light source, preparation method, and treatment schedule can vary.

Why PDT may be considered for a broader sun-damaged area

When several actinic keratoses appear across the hands or forearms, there may also be early abnormal cells that are not yet clearly visible. This pattern is sometimes described as field damage. Rather than treating only one isolated spot, a field-directed approach may address a defined area of chronically sun-damaged skin.

PDT is one of several field-directed options. Others may include prescription topical medications or procedures selected according to the location and character of the lesions. Thick, raised, horn-like, bleeding, or otherwise concerning growths may require a different approach or further evaluation before field treatment.

What treatment may feel like

During light activation, people may experience warmth, tingling, stinging, or burning. The intensity varies based on the treatment area, the light source, the medication, and individual sensitivity. Your clinical team may use cooling measures or other comfort strategies during the session.

Afterward, the hands or forearms may become red, tender, swollen, dry, crusted, or flaky. The reaction can be more noticeable in areas with greater sun damage. Recovery is variable, so your dermatologist should explain what is expected for your specific treatment plan.

Preparing for PDT

Before scheduling treatment, tell your dermatologist about prescription medications, over-the-counter products, supplements, allergies, prior skin cancers, immune system conditions, and any history of unusual reactions to light. Your clinician may also ask about recent sun exposure and skincare products used on the area.

Follow the office’s instructions about whether to pause exfoliating acids, retinoids, scrubs, or other irritating products. Do not stop a prescription medication unless the prescribing clinician tells you to do so.

Caring for the skin after treatment

Post-treatment instructions should take priority because recommendations can vary. Conservative care may include:

• Keeping the treated area protected from sunlight and bright visible light for the period specified by your clinician.
• Using a gentle cleanser and bland moisturizer if recommended.
• Avoiding picking, peeling, scrubbing, or aggressively exfoliating the skin.
• Temporarily avoiding hot tubs, saunas, intense exercise, or other heat exposure if advised.
• Wearing protective clothing, such as tightly woven long sleeves or sun-protective gloves, when appropriate.
• Using broad-spectrum sunscreen once your clinician says it can be applied comfortably.

Hands are frequently washed and exposed to friction, household products, and sunlight, so following aftercare instructions can be especially important. Ask how to manage handwashing, driving, outdoor activities, and work responsibilities during recovery.

When to see a dermatologist

Any new, persistent, or changing growth on a sun-exposed area deserves professional evaluation. Arrange an appointment promptly for a spot that:

• Bleeds without an obvious injury.
• Becomes increasingly tender or painful.
• Grows quickly or develops a firm raised area.
• Forms a thick scale, crust, or horn-like projection.
• Does not heal or repeatedly breaks open.
• Changes noticeably in color, shape, or texture.

A dermatologist may need to examine or biopsy an individual lesion before deciding whether PDT is appropriate. PDT is not a substitute for evaluating a spot that could represent an invasive skin cancer.

Frequently asked questions

Can PDT treat several spots at the same time?

It may be used across a defined area containing multiple actinic keratoses. The size of the treatment field and the number of sessions depend on the examination and treatment protocol.

Is PDT appropriate for every actinic keratosis?

No. The location, thickness, appearance, and diagnosis of each lesion matter. Very thick or suspicious growths may need individual treatment or a biopsy rather than field-directed PDT.

Will the treated skin react visibly?

A visible inflammatory reaction is common. Redness, tenderness, peeling, crusting, and swelling may occur, but the degree and duration vary. Your dermatologist can explain the expected response and provide individualized aftercare instructions.

Why is light avoidance important after PDT?

The medication can leave treated skin temporarily sensitive to light. Exposure during this period may intensify the reaction, so follow the specific light-avoidance instructions provided by the office.

Can PDT prevent future sun damage?

PDT addresses selected existing areas of abnormal skin but does not prevent new ultraviolet damage. Ongoing sun protection, regular skin checks, and follow-up visits remain important.

How do I know whether a rough spot is an actinic keratosis?

Several benign and cancerous conditions can look similar. A dermatologist can examine the area and determine whether monitoring, treatment, or a biopsy is appropriate.

At Waverly DermSpa, we offer Photodynamic Therapy (PDT) and can help you understand whether it may be appropriate.

This article is for educational purposes and is not medical advice. For diagnosis and personalized treatment, please book an appointment with a board-certified dermatologist.

Sources & further reading

• American Academy of Dermatology (AAD) – Actinic keratosis: Diagnosis and treatment
• DermNet – Actinic keratosis