P03.001 Basal cell carcinoma

Basal cell carcinoma (BCC) is the most common type of skin cancer, arising from the basal cells in the epidermis. It is a slow-growing malignancy that rarely metastasizes but can cause significant local tissue destruction if not treated appropriately. This detailed note will cover the etiology, clinical features, diagnosis, treatment, and prevention of BCC, tailored for students preparing for the Professional and Linguistic Assessments Board (PLAB) exam.

Introduction

Basal cell carcinoma accounts for about 80% of all non-melanoma skin cancers. It predominantly affects areas of the skin exposed to sunlight, particularly the face, ears, neck, scalp, shoulders, and back.

Etiology

Risk Factors

• UV Radiation: Chronic sun exposure is the most significant risk factor.
• Skin Type: Fair-skinned individuals with light hair and eye color are at higher risk.
• Age: More common in older adults.
• Gender: Slightly more prevalent in men than women.
• Genetics: Family history of skin cancer increases risk.
• Immunosuppression: Individuals with weakened immune systems, such as organ transplant recipients, are at higher risk.
• Exposure to Carcinogens: Arsenic exposure and ionizing radiation can contribute to BCC development.

Clinical Features

Common Presentations

1. Nodular BCC: Most common type, appearing as a pearly or translucent nodule with telangiectasia. May ulcerate and form a central depression.
2. Superficial BCC: Presents as a scaly, erythematous patch, often on the trunk.
3. Morpheaform/Sclerosing BCC: Appears as a scar-like, indurated plaque, often difficult to diagnose clinically.
4. Pigmented BCC: Contains melanin, appearing darker, which can mimic melanoma.

Symptoms

• Painless, slowly growing lesion.
• Bleeding or ulceration in advanced stages.
• Itching or tenderness in some cases.

Diagnosis

Clinical Examination

• Detailed inspection of the lesion with attention to characteristic features.
• Dermatoscopy may assist in identifying specific patterns like arborizing vessels and translucency.

Biopsy

• Punch Biopsy: A small sample is taken for histopathological examination.
• Excisional Biopsy: Entire lesion removed if small, preferred for definitive diagnosis.

Histopathology

• Basaloid cells with peripheral palisading.
• Presence of mucinous stroma.
• Sometimes, perineural invasion in aggressive types.

Treatment

Surgical Options

1. Excisional Surgery: Preferred method with clear margins.
2. Mohs Micrographic Surgery: Highest cure rate, used for high-risk or recurrent BCC.
3. Curettage and Electrodessication: Suitable for small, low-risk lesions.

Non-Surgical Options

1. Topical Therapies: Imiquimod or 5-fluorouracil for superficial BCC.
2. Cryotherapy: Freezing the lesion with liquid nitrogen.
3. Photodynamic Therapy: Using photosensitizing agents and light exposure.

Radiation Therapy

• Used for patients who are not surgical candidates or for lesions in difficult-to-treat areas.

Systemic Therapy

• Hedgehog Pathway Inhibitors (e.g., Vismodegib, Sonidegib): For advanced or metastatic BCC.

Prevention

• Sun Protection: Use of broad-spectrum sunscreens, protective clothing, and avoidance of peak sun hours.
• Regular Skin Checks: Self-examination and regular dermatologist visits for high-risk individuals.
• Avoidance of Tanning Beds: Artificial UV exposure is a significant risk factor.

Points to Remember

• BCC is the most common skin cancer but rarely metastasizes.
• Chronic sun exposure is the most significant risk factor.
• Lesions often present as pearly nodules with telangiectasia or as erythematous patches.
• Diagnosis is confirmed by biopsy, with histopathology showing basaloid cells and peripheral palisading.
• Treatment options include surgical excision, Mohs surgery, topical therapies, and radiation.
• Prevention focuses on sun protection and regular skin examinations.

Bibliography

1. Habif, T.P. (2016). Clinical Dermatology: A Color Guide to Diagnosis and Therapy. Elsevier.
2. Bolognia, J., Schaffer, J.V., & Cerroni, L. (2018). Dermatology. Elsevier.
3. Marks, R., Roxburgh, C., & Selva-Nayagam, P. (2014). Skin Cancer: Recognition and Management. Wiley-Blackwell.
4. National Comprehensive Cancer Network (NCCN). (2020). Basal Cell Skin Cancer Guidelines.