Cutaneous squamous cell carcinoma
Cutaneous squamous cell carcinoma is the second most common skin cancer, a malignant neoplasm of keratinocytes driven mainly by cumulative ultraviolet exposure, that unlike basal cell carcinoma carries a meaningful risk of regional and distant metastasis, especially in solid organ transplant recipients. Diagnosis is confirmed by biopsy showing keratin pearls and dermal invasion, and management is risk-stratified by tumor site, size, thickness, differentiation, and perineural invasion, ranging from topical fluorouracil or destructive therapy for in-situ disease to Mohs micrographic surgery for high-risk tumors and cemiplimab for locally advanced or metastatic disease.
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What this article covers
- Overview
Definition: cutaneous squamous cell carcinoma (SCC) is a malignant neoplasm of epidermal keratinocytes that can invade past the epidermis into the dermis.
- Epidemiology
Typical patient: an older adult, often a man, with a long history of cumulative sun exposure and outdoor occupation (farming, construction).
- Risk factors
Ultraviolet light and ionizing radiation: the dominant cause; SCC typically arises within a field of chronic UV damage marked by actinic keratoses.
- Pathophysiology
Cell of origin: SCC arises from keratinocytes of the epidermis and can invade through the basement membrane into the dermis.
- Clinical features
Invasive SCC (most common presentation): a firm, indurated, pink-to-red hyperkeratotic papule, plaque, or nodule with adherent scale that may ulcerate, bleed, or crust; the palpable induration (it…
- Differential diagnosis
Amelanotic melanoma: the most dangerous mimic to miss; a pink or red nodule lacking pigment, sometimes with subtle vascular structures on dermoscopy; biopsy is required to distinguish it from SCC.
- Diagnosis
First, biopsy establishes the diagnosis: shave, punch, or excisional biopsy showing full-thickness keratinocyte atypia with keratin pearl formation and invasion into the dermis confirms invasive SCC…
- Management
First, confirm the high-risk feature status established in Diagnosis (site, diameter, thickness, differentiation, perineural invasion), since it determines which treatment pathway below applies.
- Complications
Regional and distant metastasis: uncommon overall but the defining risk separating SCC from BCC; risk rises sharply with high-risk features, perineural invasion, and immunosuppression, reaching approximately 8% in transplant recipients.
- Prognosis
Generally favorable when treated early: most low-risk SCC is cured with surgical excision alone.
- Prevention
Routine sunscreen use: apply a sunscreen with sun protection factor greater than 35, using about 2 mg per square centimeter of exposed skin (roughly 30 mL for the body in swimwear and 5 mL for the…
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Basal cell carcinoma is the most common skin cancer, arising from the basal layer of the epidermis after ultraviolet-driven mutation of the PTCH tumor-suppressor gene, and it rarely metastasizes but can cause significant local tissue destruction if untreated. Diagnosis is confirmed by shave or punch biopsy, and treatment is chosen by risk: standard excision or Mohs micrographic surgery for higher-risk tumors, with curettage and electrodesiccation or topical imiquimod or fluorouracil reserved for low-risk superficial or nodular disease.
- Actinic keratosis
Actinic keratosis is a precancerous, gritty, sandpaper-like scaly macule or papule on chronically sun-exposed skin that carries a 5 to 10 percent lifetime risk of progressing to squamous cell carcinoma. Isolated lesions are destroyed with cryotherapy, while numerous lesions marking a field of sun damage are treated with topical fluorouracil, imiquimod, or photodynamic therapy to clear subclinical disease and prevent skin cancer.
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