Basal cell carcinoma (BCC) is the most frequently diagnosed form of skin cancer worldwide.

Originating from the basal cells in the lowest layer of the epidermis, it typically develops in sun-exposed areas of the skin, especially the face, neck, and arms.

What is Basal Cell Carcinoma?

Basal cell carcinoma arises due to abnormal, uncontrolled proliferation of basal cells, which normally function as regenerative cells producing new skin. The cancerous growth forms lesions that can appear as pearly or flesh-colored nodules, sometimes accompanied by visible blood vessels (telangiectasia), sores that do not heal, or scaly patches. Various subtypes exist, including nodular, superficial, and morpheaform types, each with distinct clinical and microscopic characteristics.

Causes and Risk Factors

The primary cause of basal cell carcinoma is prolonged and cumulative exposure to ultraviolet (UV) radiation from sunlight or artificial sources such as tanning beds. UV radiation induces DNA damage in skin cells, triggering mutations that promote malignant transformation. Fair-skinned individuals, especially those with light hair and eye color, carry a significantly higher risk due to lower melanin protection.

Additional risk factors include:

- History of intense, intermittent sun exposure or sunburns

- Advanced age, as damage accumulates over time

- Previous radiation therapy

- Genetic predispositions like xeroderma pigmentosum that impair DNA repair

- Immunosuppression, which diminishes surveillance against malignant cells

Clinical Features and Diagnosis

Basal cell carcinoma (BCC) typically develops slowly, appearing first as small, pearly nodules that may ulcerate or bleed. If left untreated, these tumors can enlarge and invade deeper skin though metastasis is exceedingly rare. Diagnosis is confirmed by skin biopsy, which usually shows nests or cords of basaloid cells with peripheral palisading and a mucinous or myxoid stroma. Dermoscopy aids early detection by revealing characteristic features such as arborizing vessels, blue-gray ovoid nests, and shiny white streaks.

Treatment Strategies

Management of basal cell carcinoma depends on tumor size, location, histologic subtype, and patient factors. Treatment goals focus on complete tumor removal with minimal cosmetic and functional impairment. Surgical excision remains the gold standard, allowing histologic margin assessment for complete removal. Mohs micrographic surgery offers the highest cure rates—approximately 99% at five years—particularly for high-risk or recurrent tumors, by sequentially removing and examining tissue layers until margins are clear.

Other options include:

- Curettage and electrodesiccation: effective for small, low-risk lesions; less suitable for aggressive subtypes.

- Radiation therapy: an alternative for patients unsuited for surgery or for tumors in anatomically challenging locations.

- Topical agents like imiquimod and 5-fluorouracil, appropriate for superficial BCCs.

- Photodynamic therapy, using light-activated drugs to destroy cancer cells, suitable for select cases.

- Emerging targeted therapies such as hedgehog pathway inhibitors (e.g., vismodegib) offer options for advanced or metastatic BCC, though these cases are uncommon.

Prevention and Prognosis

Preventing basal cell carcinoma focuses on minimizing UV exposure through sunscreen use, protective clothing, and avoidance of tanning devices. Regular skin examinations facilitate early detection, which improves treatment outcomes and reduces the need for extensive interventions.

While BCC rarely threatens life, untreated cases can lead to significant disfigurement and functional impairment due to local tissue invasion. Early diagnosis and tailored treatment provide excellent prognosis with low recurrence rates.

Dr. Walayat Hussain, a consultant dermatologist and skin cancer expert: "Basal cell carcinoma is a type of skin cancer. As BCCs stay localized to the skin, if treated adequately by a trained specialist they can be cured in almost every case. However, the treatment can be more complicated if the BCC has been present for a long time, or if it occurs in a high-risk site such as close to the eye or on the nose or ear."

Basal cell carcinoma is the most common skin cancer, principally caused by UV radiation exposure and affecting primarily sun-exposed skin. Though its progression is generally slow and metastasis rare, untreated tumors pose risks of significant local damage.

Diagnosis through clinical and histological methods allows for multiple effective treatment options, ranging from surgical excision to topical therapies. Preventive measures emphasizing UV protection and regular skin monitoring remain critical in reducing incidence and ensuring timely intervention.