Basal cell carcinoma
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.
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What this article covers
- Overview
Definition: basal cell carcinoma (BCC) is a malignant neoplasm arising from the basal layer of the epidermis.
- Epidemiology
Population burden: nonmelanoma skin cancers, principally basal cell and squamous cell carcinoma, are the most common malignancies diagnosed in the United States.
- Risk factors
Ultraviolet light exposure: the major risk factor, with basal cell carcinoma more strongly correlated with sun exposure at a younger age and intense, intermittent exposure than squamous cell carcinoma.
- Pathophysiology
Cell of origin: BCC arises from the basal layer of the epidermis, the germinative layer responsible for keratinocyte renewal.
- Clinical features
Nodular BCC (most common): a pearly or translucent nodule or papule with arborizing telangiectasias, often with a central depression or ulceration and a rolled, waxy border classically called a…
- Differential diagnosis
Actinic keratosis: rough, scaly, and often tender on palpation, without the pearly translucency or rolled border seen in superficial or nodular BCC.
- Diagnosis
First, biopsy establishes the diagnosis: a shave or punch biopsy confirms BCC and shows the classic pattern of basaloid cell nests with peripheral palisading and retraction artifact (clefting) between tumor and dermis.
- Management
First, risk-stratify the tumor by subtype, size, location, and whether it is primary or recurrent, since this determines which of the following options is appropriate.
- Complications
Local tissue destruction: untreated basal cell carcinomas can enlarge and cause significant local tissue damage if left in place for a prolonged period.
- Prognosis
Generally excellent: BCC usually grows slowly and is locally invasive rather than aggressive, and it is rarely fatal.
- Prevention
Routine sunscreen use: apply a sunscreen with a sun protection factor greater than 35 as a routine measure to reduce cumulative ultraviolet exposure.
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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.
- Melanoma
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- Seborrheic keratosis
Seborrheic keratosis is an extremely common benign epidermal growth of older adults that presents as a round or oval, sharply demarcated, waxy or verrucous plaque with a classic stuck-on appearance on the face, trunk, or upper extremities. Diagnosis is clinical based on the stuck-on morphology; no treatment is required, and irritated or cosmetically bothersome lesions can be removed by cryotherapy, curettage, or shave removal.