Years of sun exposure can leave more than visible signs of aging. On areas such as the scalp, chronic ultraviolet damage can lead to actinic keratoses (AKs)—rough, scaly lesions that are considered precancerous.
When numerous or persistent actinic keratoses develop across a sun-damaged area, treating one spot at a time may not always be the preferred approach. Photodynamic therapy (PDT) offers another way to treat precancerous lesions across a broader treatment field.
Recently, a 75-year-old man returned to Village Dermatology for his second red-light PDT treatment for actinic keratoses of the scalp. He had previously undergone PDT in December 2025 but continued to have a hypertrophic, scaly actinic keratosis requiring further treatment.
His case raises a question many patients have:
"If I've already had photodynamic therapy once, why do I need another treatment?"
What Is an Actinic Keratosis?
An actinic keratosis is a precancerous skin growth that develops after accumulated ultraviolet exposure.
AKs commonly appear on chronically sun-exposed areas such as the:
Scalp
Forehead
Face
Ears
Forearms
Backs of the hands
They may feel rough before they become especially noticeable visually.
During this patient's examination, the scalp lesion appeared as a thickened red papule with hyperkeratotic scale, consistent with a hypertrophic actinic keratosis.
Are Actinic Keratoses Skin Cancer?
Actinic keratoses are precancerous lesions, not automatically skin cancer.
However, a small subset of untreated AKs can progress to squamous cell carcinoma (SCC). This is why dermatologists recommend monitoring and treating suspicious or persistent lesions rather than simply ignoring them.
Patients should also contact their dermatologist when a treated lesion fails to resolve or begins changing.
Why Are Actinic Keratoses So Common on the Scalp?
The scalp can receive decades of cumulative ultraviolet exposure, particularly when hair coverage becomes thinner with age.
That makes it a common location for chronic sun damage and actinic keratoses.
Once significant sun damage has accumulated, a patient may have not only visible AKs but also surrounding areas of damaged skin where additional lesions may eventually appear.
Consistent sun protection therefore remains important even after treatment.
Why Might Someone Need More Than One PDT Treatment?
Photodynamic therapy isn't necessarily a one-and-done procedure.
Some patients require more than one treatment depending on the:
Number of lesions
Thickness of individual AKs
Amount of surrounding sun damage
Response to the first treatment
Treatment plan established by the dermatologist
For this patient, the current visit represented PDT treatment number two for his scalp.
The goal was to continue treating the precancerous lesions and sun-damaged treatment field.
How Does Photodynamic Therapy Work?
PDT combines a photosensitizing medication with a specific wavelength of light.
For this patient's procedure, Ameluz® was applied to the scalp. The treatment area was then exposed to a 635-nanometer red LED light source for 30 minutes.
The medication makes targeted abnormal cells more sensitive to light. Illumination then activates the medication within the treatment area.
This approach allows dermatologists to treat actinic keratoses without surgically removing every individual lesion.
Why Was the Thick Scale Removed Before Treatment?
Before the photosensitizing medication was applied, the patient's thicker hyperkeratotic lesions were gently curetted.
Thick scale can act as a barrier over the surface of an actinic keratosis.
Removing excess keratin helps prepare the lesion and can make the abnormal area more amenable to treatment.
After preparation, the scalp was cleaned and the medication was applied before red-light illumination.
What Happens During Red-Light PDT?
The patient's treatment followed several steps:
The scalp was examined and the treatment area identified.
Hyperkeratotic lesions were curetted.
The treatment area was cleaned and prepared.
Ameluz® was applied to the scalp.
Protective eyewear was placed.
The scalp was illuminated using 635 nm red LED light for 30 minutes.
Detailed post-treatment instructions were reviewed.
The procedure was performed as treatment for medically necessary precancerous lesions.
What Should I Expect After PDT?
Photodynamic therapy intentionally produces an inflammatory response in treated sun-damaged skin.
Following treatment, patients may experience:
Sunburn-like redness
Tenderness or discomfort
Crusting
Scabbing
Temporary swelling
Skin sensitivity
The intensity of the reaction varies between patients and depends partly on the treatment area and extent of sun damage.
Pigmentary changes, blistering, and, rarely, scarring are also potential risks discussed before treatment.
Why Is Avoiding Sunlight So Important After PDT?
The photosensitizing medication can leave treated skin temporarily very sensitive to light.
This patient was specifically instructed to avoid sunlight for the next two days and use appropriate sun protection.
Ignoring these instructions can intensify the skin reaction.
Patients should follow the post-procedure directions provided by their dermatologist rather than relying only on their normal sunscreen routine immediately after PDT.
Can Actinic Keratoses Come Back After Treatment?
Yes.
PDT treats existing areas of abnormal sun-damaged skin, but it cannot erase the cumulative ultraviolet exposure that occurred throughout a patient's lifetime.
New actinic keratoses may therefore develop in the future.
Long-term prevention includes:
Broad-spectrum SPF 30+ sunscreen
Hats and sun-protective clothing
Limiting unnecessary UV exposure
Regular dermatologic examinations
Prompt evaluation of new or changing lesions
Patients with significant sun damage may need ongoing surveillance and additional treatments over time.
Are There Other Ways to Treat Actinic Keratoses?
Yes. PDT is one of several available treatments.
Depending on the number, thickness, location, and appearance of the lesions, options may include:
Cryotherapy
Photodynamic therapy
Topical 5-fluorouracil (5-FU)
Imiquimod
Other individualized treatment approaches
The best option isn't necessarily the same for every patient or every actinic keratosis.
When Should a Treated Scalp Lesion Be Rechecked?
Patients should contact their dermatologist if an actinic keratosis:
Doesn't resolve despite treatment
Becomes increasingly thick
Rapidly enlarges
Develops persistent tenderness
Bleeds repeatedly
Produces concerning changes
Causes an unexpectedly severe treatment reaction
Persistent or changing lesions may require additional evaluation to determine whether another treatment or diagnostic procedure is appropriate.
Actinic Keratosis and Photodynamic Therapy in Houston & Katy, Texas
If years of Texas sun exposure have left your scalp or face covered with rough, scaly spots, those changes shouldn't automatically be dismissed as normal aging.
At Village Dermatology, our dermatology team evaluates and treats actinic keratoses and chronically sun-damaged skin using individualized approaches including cryotherapy, topical therapies, and photodynamic therapy when appropriate.
For patients with persistent or widespread scalp actinic keratoses, repeat PDT may be incorporated into a longer-term treatment and skin-cancer prevention strategy.
Schedule an evaluation with Village Dermatology in Houston or Katy, Texas, if you have rough, scaly, or changing areas of sun-damaged skin that aren't going away.
