Skin Cancer · Burien & Bellevue, WA
Squamous Cell Carcinoma
The second most common skin cancer in the United States, with a meaningful risk of spreading — especially in immunosuppressed patients. Early diagnosis and appropriate treatment are key to excellent outcomes.
Schedule an AppointmentWhat Is Squamous Cell Carcinoma?
Squamous cell carcinoma (SCC) is a malignant tumor arising from squamous cells — the flat cells that make up the majority of the outer skin layer. It is the second most common skin cancer in the United States, with approximately 1.8 million new cases diagnosed annually. Like basal cell carcinoma, SCC is primarily caused by cumulative ultraviolet (UV) radiation exposure from the sun or tanning devices.
SCC is more serious than BCC because it carries a 2–5% risk of metastasizing to lymph nodes and distant organs. This risk rises substantially in patients who are immunosuppressed. Despite this, the vast majority of SCCs are diagnosed at an early stage when they are highly curable with appropriate treatment.
How Does SCC Appear?
SCC can present in several ways. Common features include:
- A firm, red nodule or plaque with a rough, scaly, or crusted surface
- A flat lesion with a scaly, crusted surface — often resembling a persistent eczema patch or abrasion
- A new wart-like growth that may bleed when touched
- An open sore or ulcer that does not heal, or that heals and reopens
- A rough patch in or around an old scar or chronic wound
- A raised growth with a central depression or crater, sometimes with a rolled edge
SCCs most commonly appear on sun-exposed areas: the face, scalp, ears, neck, backs of the hands, and forearms. They can also develop on the lower lip, mucous membranes, and in the genital region in association with HPV infection.
Actinic Keratosis: The Precursor to SCC
Actinic keratoses (AKs) are pre-cancerous lesions that represent the earliest recognizable step in the continuum toward invasive SCC. They appear as rough, scaly, sometimes slightly raised patches — often pink, red, or flesh-colored — on chronically sun-exposed skin. They may feel like sandpaper when you run your finger over the skin, even before they are visible.
Individual AKs have a low annual risk of transforming into invasive SCC, but patients who develop AKs typically have many of them simultaneously. The cumulative risk over time, across multiple lesions, is significant. Additionally, it is not possible to predict which individual AK will progress. For this reason, dermatologists recommend treating AKs as they are identified.
AK treatment options include cryotherapy (liquid nitrogen), topical field therapy with 5-fluorouracil cream, imiquimod, tirbanibulin, or photodynamic therapy for patients with extensive field cancerization.
Risk Factors for SCC
- Cumulative UV exposure — sun and tanning beds
- Fair skin, light eyes, and a history of sunburns
- Immunosuppression — organ transplant recipients have 65–250× the normal SCC risk
- Human papillomavirus (HPV) infection — particularly for SCCs of the genitals, perianal skin, and lips
- Chronic wounds, scars, ulcers, or areas of prior radiation
- Exposure to arsenic, coal tar, or certain industrial chemicals
- History of actinic keratoses or prior SCC
- Smoking (strongly associated with SCC of the lips)
High-Risk Features That Warrant Aggressive Treatment
Not all SCCs carry the same risk. The following features identify tumors that require more aggressive management — typically Mohs surgery with close follow-up:
- Tumor diameter greater than 2 cm
- Depth of invasion beyond 2 mm or into subcutaneous fat
- Location on the ear, lip, scalp, nose, or non-sun-exposed skin
- Poorly differentiated or undifferentiated histology on pathology
- Perineural invasion (tumor growing along nerves) — associated with much higher recurrence and metastasis rates
- Arising within a chronic scar, burn wound, or radiation field
- Patient is immunosuppressed
- Recurrent tumor (previously treated and returned)
Treatment Options for SCC
Mohs Micrographic Surgery
The preferred treatment for high-risk SCCs — those on the face, head, or neck; those with poorly defined borders; aggressive histologic subtypes; and recurrent tumors. Mohs achieves the highest cure rates (approximately 94% for primary SCC) while preserving the maximum normal tissue. Its complete margin assessment is especially important for SCCs with perineural invasion.
Standard Surgical Excision
Appropriate for well-differentiated, low-risk SCCs on the trunk and extremities. A 4–6 mm margin is typically taken around the clinical tumor, and the specimen is sent for standard pathologic analysis. Cure rates are high for truly low-risk tumors treated with adequate margins.
Electronic Brachytherapy (eBT)
A surgery-free radiation alternative for patients who cannot safely undergo surgery — particularly elderly patients, those on blood thinners, or those with tumors in cosmetically sensitive areas. eBT delivers curative radiation in 8 outpatient sessions over four weeks.
Electrodesiccation & Curettage (ED&C)
Reserved for very small, well-differentiated, superficial SCCs on low-risk anatomic sites such as the trunk and extremities. Not appropriate for the face or for any high-risk features.
Schedule a Skin Check
Rough patches, non-healing sores, or wart-like growths on sun-exposed skin deserve prompt evaluation. Our dermatologists can assess and biopsy suspicious lesions at our Burien and Bellevue offices.
Schedule an AppointmentQuick Facts
- ~1.8 million cases diagnosed in the US annually
- 2–5% risk of metastasis overall
- Higher metastasis risk in immunosuppressed patients
- Actinic keratosis is a direct SCC precursor
- Mohs surgery preferred for high-risk tumors
- Most curable when caught early
Frequently Asked Questions
What is the difference between SCC and basal cell carcinoma?
Both are non-melanoma skin cancers caused primarily by UV exposure, but they behave differently. BCC almost never metastasizes (spreads to other organs), while SCC carries a 2–5% overall risk of metastasis — higher in immunosuppressed patients or for high-risk tumor locations. SCC also tends to grow faster than BCC. Both are highly curable when treated early, and Mohs surgery is the preferred approach for high-risk tumors of either type.
What is actinic keratosis and does it always turn into SCC?
Actinic keratosis (AK) is a pre-cancerous scaly patch caused by chronic UV exposure. It represents the earliest stage in the SCC spectrum. Not every AK will progress to SCC — the estimated risk per individual AK is less than 1% per year — but with multiple AKs present over years, the cumulative risk is meaningful. Treatment of AKs (with liquid nitrogen, topical 5-FU, imiquimod, ingenol mebutate, or photodynamic therapy) is recommended to prevent progression.
Which SCCs are considered high risk?
High-risk features include: tumor diameter >2 cm; tumor depth >2 mm or invasion into subcutaneous tissue; location on the ear, lip, scalp, or non-sun-exposed skin (which may indicate an unusual origin); poorly differentiated or undifferentiated histology; perineural or lymphovascular invasion; development within a chronic wound, scar, or radiation field; and immunosuppression in the patient. High-risk SCCs should be treated with Mohs surgery to ensure complete margin clearance.
Can SCC spread to lymph nodes?
Yes. SCC can metastasize — most often first to the regional lymph nodes. Overall, about 2–5% of SCCs spread, but this rises significantly in patients who are immunosuppressed (e.g., organ transplant recipients), where metastasis rates can exceed 10%. High-risk tumor features further elevate this risk. If metastasis is suspected, imaging studies and lymph node evaluation are recommended.
What does squamous cell carcinoma feel like?
SCC often presents as a rough, scaly, or crusty patch — similar to a wart or a persistent scrape. It may be raised or flat, and the surface may feel hard or firm when touched. Some SCCs are tender or painful; others are asymptomatic. An open sore that does not heal within several weeks, or a rough patch that returns after being picked off, is a common presentation that warrants evaluation.
Is SCC more common in transplant patients?
Yes, significantly so. Organ transplant recipients on long-term immunosuppressive therapy have a 65–250 times higher risk of developing SCC compared to the general population. The risk is highest for heart transplant recipients. The SCCs that arise in transplant patients tend to be more numerous, more aggressive, and more likely to metastasize, making regular dermatology surveillance every 3–6 months essential in this population.
Expert SCC Care in Burien & Bellevue
From actinic keratosis treatment to Mohs surgery for high-risk squamous cell carcinoma, Dermatology of Seattle provides comprehensive, evidence-based care at two convenient locations.