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Basal Cell Carcinoma

Basics

  • Most common type of skin cancer worldwide
  • Originates from basal cell layer of skin appendages
  • Rarely metastasizes but locally invasive causing tissue destruction and disfigurement

Epidemiology

  • Most common cancer in Europe, Australia, USA

  • 2 million new cases annually in the USA

  • White individuals: 1 in 5 lifetime risk
  • Male > female (2:1 ratio)
  • Predominantly affects >60 years old
  • Common in Asian and Hispanic individuals; 2nd most common in African Americans

Etiology and Pathophysiology

  • UV radiation induces inflammation and cyclooxygenase activation
  • Genetic syndromes: albinism, xeroderma pigmentosum, Gorlin syndrome, Bazex-Dupré-Christol
  • Mutations in patched tumor suppressor gene and smoothened leading to hedgehog pathway upregulation

Risk Factors

  • Chronic UV/sun exposure (skin types I and II at higher risk)
  • Light complexion, red/blond hair, blue/green eyes
  • Male sex, tanning bed use
  • Prior nonmelanoma skin cancer
  • Immunosuppression (transplant, HIV)
  • Arsenic exposure

Diagnosis

History

  • History of chronic sun exposure
  • Slowly growing, ulcerating, or bleeding lesion on sun-exposed skin

Physical Exam

  • 80% lesions on face and neck, 20% on trunk and limbs
  • Nodular (50-80%): pearly papule with telangiectasia, rolled border, possible ulceration
  • Pigmented: resembles melanoma, blue/brown/black hue
  • Superficial: red, scaly plaque with thin rolled borders, central clearing, usually trunk/extremities
  • Morpheaform: scar-like, waxy plaque with poorly defined borders, often head/neck

Differential Diagnosis

  • Squamous cell carcinoma
  • Melanoma (pigmented lesions)
  • Actinic keratosis
  • Sebaceous hyperplasia
  • Epidermal inclusion cyst
  • Others (psoriasis, molluscum contagiosum)

Diagnostic Tests

  • Biopsy mandatory (shave for nodular, punch or scoop for flat lesions)
  • Dermoscopy improves accuracy
  • Histology: basaloid cells with peripheral palisading, mucinous stroma in nodular subtype

Treatment

General Measures

  • Low-risk BCC: curettage and electrodesiccation, standard excision, radiation therapy
  • High-risk BCC: Mohs micrographic surgery, radiation therapy

Medical Therapy

  • 5-Fluorouracil cream for superficial low-risk lesions (5% BID for 3-10 weeks)
  • Imiquimod cream for low-risk superficial BCC (daily 6-12 weeks, ~80% clearance)
  • Emerging: Vismodegib (hedgehog pathway inhibitor) for advanced/multiple BCCs

Surgery

  • Mohs surgery preferred for high-risk, recurrent, or aggressive tumors
  • Curettage and electrodesiccation for small nodular lesions <1 cm in low-risk areas
  • Standard excision with 4-mm margins for low-risk lesions <2 cm
  • Radiation therapy for patients unsuitable for surgery or as adjuvant therapy

Other

  • Cryotherapy reserved for nodular/superficial lesions, contraindicated in hair-bearing areas and lower limbs
  • Photodynamic therapy off-label in the USA; approved in other countries

Ongoing Care and Follow-Up

  • Monitor every 6-12 months for 2-5 years, then annually lifelong
  • Advise sun protection, avoidance of tanning beds, and use of broad-spectrum sunscreen SPF ≥30
  • Skin self-exams monthly
  • Consider oral retinoids in Gorlin syndrome or severe actinic damage

Prognosis

  • 90-95% cure rate with appropriate treatment
  • Recurrences mostly within 5 years; head/neck lesions have higher recurrence risk
  • Metastasis is rare (<0.1%) but usually fatal
  • Development of new BCCs common (30-50% within 5 years)

Complications

  • Recurrence, local tissue destruction
  • Rare metastasis with risk factors: head/neck location, tumor >4 cm, deep invasion
  • Cosmetic disfigurement, infection of ulcerated lesions

Clinical Pearls

  • Nodular BCC most common subtype with telangiectasia and rolled border
  • Chronic sun exposure and fair skin are primary risks
  • Mohs surgery offers best margin control for high-risk lesions
  • Biopsy is necessary for diagnosis and subtype identification