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Squamous cell carcinoma
What is cutaneous squamous cell carcinoma?
Cutaneous squamous cell carcinoma (SCC) is a common type of keratinocytic or non-melanoma skin cancer. It is derived from cells within the epidermis that make keratin — the horny protein that makes up skin, hair and nails.
Cutaneous SCC is an invasive disease, referring to cancer cells that have grown beyond the epidermis. SCC can sometimes metastasise (spread to distant tissues) and may prove fatal.
Who gets cutaneous squamous cell carcinoma?
Risk factors for cutaneous SCC include:
- Age and gender: SCCs are particularly prevalent in elderly males. However, they also affect females and younger adults.
- Previous SCC or other form of skin cancer (basal cell carcinoma, melanoma)
- Actinic keratoses
- Outdoor occupation or recreation
- Smoking
- Fair skin, blue eyes and blond or red hair
- Previous cutaneous injury, thermal burn, disease (eg cutaneous lupus, epidermolysis bullosa, leg ulcer)
- Inherited syndromes: SCC is a particular problem for families with xeroderma pigmentosum and albinism
- Other risk factors include ionising radiation, exposure to arsenic, and immune suppression due to disease (eg chronic lymphocytic leukaemia) or medicines. Organ transplant recipients have a massively increased risk of developing SCC.
What are the clinical features of cutaneous squamous cell carcinoma?
Cutaneous SCCs present as enlarging scaly or crusted lumps. They usually arise within pre-existing actinic keratosis or intraepidermal carcinoma.
- They grow over weeks to months
- They may ulcerate
- They are often tender or painful
- Located on sun-exposed sites, particularly the face, lips, ears, hands, forearms and lower legs
- Size varies from a few millimetres to several centimetres in diameter.
Squamous cell carcinoma
How is squamous cell carcinoma diagnosed?
Diagnosis of cutaneous SCC is based on clinical features. The diagnosis and histological subtype is confirmed pathologically by diagnostic biopsy or following excision.
Patients with high-risk SCC may also undergo staging investigations to determine whether it has spread to lymph nodes or elsewhere. These may include:
- Imaging using ultrasound scan, X-rays, CT scans, MRI scans
- Lymph node or other tissue biopsy
What is the treatment for cutaneous squamous cell carcinoma?
Cutaneous SCC is nearly always treated surgically. Most cases are excised with a 3–10 mm margin of normal tissue around the visible tumour. A flap or skin graft may be needed to repair the defect.
Other methods of removal include:
- Shave, curettage, and electrocautery for low-risk tumours on trunk and limbs
- Aggressive cryotherapy for very small, thin, low-risk tumours
- Mohs micrographic surgery for large facial lesions with indistinct margins or recurrent tumours
- Radiotherapy for inoperable tumour, patients unsuitable for surgery, or as adjuvant
What is the treatment for advanced or metastatic squamous cell carcinoma?
Locally advanced primary, recurrent or metastatic SCC requires multidisciplinary consultation. Often a combination of treatments is used.
- Surgery
- Radiotherapy
- Experimental targeted therapy using epidermal growth factor receptor inhibitors
Courtesy of Derm Net NZ
Images British Skin Foundation
