actinic keratosis

Actinic Keratosis & Squamous Cell Carcinoma

Omar Y. Abdullah

What is your differential diagnosis?

Actinic keratosis
Basal cell carcinoma
Melanoma
Seborrheic keratosis
Squamous cell carcinoma
Verruca vulgaris

Management

What is your next step in management?
Liquid nitrogen cryotherapy
Reassurance with close follow-up
Shave biopsy
Surgical excision
Topical antibiotics


Liquid nitrogen cryotherapy (Would not treat the lesion with cryotherapy without knowing the diagnosis. This is a suspicious lesion that warrants a biopsy)
Reassurance with close follow-up (A history of a new growing lesion with concerning characteristics warrants a biopsy)
Shave biopsy (Before treating this lesion, you must establish a diagnosis)
Surgical excision (You must know the diagnosis before you can plan treatment with surgical excision and surgical margins)
Topical antibiotics (The lesion is not an infection)
Shave biopsy reveals…

Squamous cell carcinoma (SCC)

Most commonly occurs among people with white/fair skin
Commonly located on the head, neck, forearms, and dorsal hands (sun-exposed areas)
SCC has increased associated mortality compared to basal cell carcinoma, mostly due to a higher rate of metastasis

SCC: Etiology

Cell of origin: keratinocyte
Cumulative UV exposure
Cause genetic alterations, which accumulate and provide selective growth advantage
SCC arising in non sun-exposed areas may be related to chemical carcinogen exposure (e.g. arsenic)

SCC: Clinical manifestations

Various morphologies
Papule, plaque, or nodule
Pink, red, or skin-colored
Scale
Exophytic (grows outward)
Indurated (dermal thickening, lesion feels thick, firm)
May present as a cutaneous horn
Friable – may bleed with minimal trauma and then crust
Usually asymptomatic; may be pruritic

SCC in situ

Also known as Bowen’s disease
Circumscribed pink-to-red patch or thin plaque with scaly or rough surface
Keratinocyte atypia is confined to the epidermis and does not invade past the dermal-epidermal junction

Pathology reports for SCC

“Invasive squamous cell carcinoma”
Means there are SCC cells in the dermis
If there is no dermal involvement, it is squamous cell carcinoma in situ
Unrelated to metastatic potential
“Atypical squamous proliferation”
Often used when biopsy is too superficial
If dermis cannot be seen in the biopsy, invasive SCC cannot be excluded


SCC: Treatment
There are several medical and surgical treatment options
Suspicion of SCC should prompt referral to a dermatologist for evaluation and discussion of specific treatment approaches
Surgical Treatment Options
Surgical excision (standard of care for invasive SCCs)
Wide local excision
Mohs micrographic surgery
Curette and Desiccation (reserved for in situ SCC)
Non-surgical Treatment Options
Radiation therapy for poor surgical candidates
5-Fluorouracil cream, imiquimod cream, photodynamic therapy – typically reserved for in situ SCCs when excision is a suboptimal choice

SCC: Course & Prognosis

For SCC arising in sun-exposed skin, the rate of metastasis to regional lymph nodes ~ 5%
Higher rates of metastasis if:
Large (diameter > 2cm), deep (> 4mm), and recurrent tumors
Tumor involvement of bone, muscle, and nerve
Location on scalp, ears, nose, and lips
Tumor arising in scars, chronic ulcers, burns, sinus tracts, or on the genitalia
Immunosuppressed patients
Tumors caused by arsenic ingestion\


Patient Follow-up
All patients treated for cutaneous SCC need surveillance for the early recognition and management of:
Treatment-related complications
Local or regional recurrences
Development of new skin cancers
Patients with a history of SCC should have close follow-up
Patients are often seen every 6 to 12 months

Actinic Keratosis (AK)

AKs are premalignant lesions; they have the potential of transforming into a skin cancer. Virtually all AKs that transform into cancer will become squamous cell carcinoma (SCC).
Most AKs do not progress to invasive SCC
Risk of malignant transformation of an AK to SCC within one year is about 1 in 1000
Risk factors for malignant progression of AK to SCC include: persistence of the AK, history of skin cancer, and immunosuppression
The keratinocyte is the cell of origin
Actinic Keratosis
AKs may be considered as part of a disease spectrum:

AK: Etiology

Cumulative and prolonged UV exposure, resulting in:
UV-induced p53 tumor suppressor gene mutations
Individual risk factors can increase susceptibility:
Increasing age
Fair skin, light eyes/hair (skin types I,II)
Immunosuppression
Genetic syndromes, such as xeroderma pigmentosum and albinism


AK: Clinical manifestations
May be symptomatic (tender)
Located in sun-exposed areas
Head, neck, extensor forearms, and dorsal hands
Typically on background of sun damaged skin
Erythematous papule or thin plaque with a characteristic rough, gritty scale
Often diagnosed by feel (like sandpaper)

AK: Actinic cheilitis

Actinic cheilitis represents AKs on the lips, most often the lower lip
Erythematous patch with rough gritty scale involving the lower lip

AK: Treatment

There are several topical and procedural treatment options for AKs. The best option is chosen after consideration of number, location, and thickness, among other patient factors.
Therapies are considered local – treating the individual lesion, or field therapies – treating multiple AKs in one area
Consultation with a dermatologist to guide therapy may be useful
AK: Patient Education
Patients with AKs are at increased risk of developing other non-melanoma and melanoma skin cancers.
Therefore, these patients should have regular skin exams every 6-12 months
Patients should be seen prior to their regularly scheduled follow-up if they notice a concerning lesion on a self-skin exam


Patient Education: Be Sun Smart®
Generously apply a broad-spectrum, water-resistant sunscreen with a Sun Protection Factor (SPF) of 30 or more to all exposed skin.
“Broad-spectrum” provides protection from both UVA and UVB rays.
Reapply approximately every two hours, even on cloudy days, and after swimming or sweating.
Wear protective clothing, such as a long-sleeved shirt, pants, a wide-brimmed hat, and sunglasses.
Seek shade.
Remember that the sun's rays are strongest between 10 AM – 4PM.
If your shadow appears to be shorter than you are, seek shade.

Use extra caution near water, snow, and sand because they reflect and intensify the damaging rays of the sun, which can increase your chances of a sunburn.
Get vitamin D safely through a healthy diet that may include vitamin supplements. Don't seek the sun.
Avoid tanning beds. Ultraviolet light from the sun and tanning beds can cause skin cancer and wrinkling. If you want to look tan, consider using a self-tanning product, but continue to use sunscreen with it.
Check your birthday suit on your birthday. If you notice anything changing, growing, or bleeding on your skin, see a dermatologist.

Take Home Points

Indurated erythematous lesions with keratin are SCC until proven otherwise.
The diagnosis of SCC is established via shave biopsy.
The treatment of SCC is surgical excision. Radiation therapy is a good choice in poor surgical candidates.
Actinic keratoses are erythematous papules or thin plaques with scale. They feel rough on palpation but are not indurated.
Actinic keratosis is a precancerous lesion that can evolve into squamous cell carcinoma.
The treatment for actinic keratoses depends on the number of lesions and the patient’s preference.