Malignant Neoplasms of the Skin: Basal Cell Carcinoma

Malignant Neoplasms of the Skin

Basal Cell Carcinoma (Rodent Ulcer)

• A locally malignant lesion that arises from the basal cells of the epidermis
• More common in males above 40 years old
• Most common malignant lesion of the skin
• Predisposing factors:
  • Prolonged exposure to UV rays
  • Light-colored complexion
  • Albinism and xeroderma pigmentosum
  • Ionizing radiation
  • Immunodeficiency

Gross Appearance

• Usually starts as a small nodule covered by thin epidermis
• Ulcerates, producing serous discharge and bleeding
• Edge of the ulcer is rolled-in and beaded
• Rate of growth is very slow
• Two types: excavating (deeply infiltrating) and superficial spreading (resembling psoriasis or eczema)

Microscopic Appearance

• Tumor cells arranged as nests or sheets
• Outer layer composed of low columnar cells with tall nuclei
• Inner layer composed of polyhedral cells with large basophilic nuclei
• No tendency to keratinization and mitotic figures are uncommon

Spread and Treatment

• Direct spread to surrounding and underlying structures
• No lymphatic or blood spread
• Treatment: radiotherapy or surgery, with a safety margin of 0.5cm
• Prognosis: excellent, with a 100% cure rate if excised completely

Squamous Cell Carcinoma (Epithelioma)

• More common in elderly males
• Predisposing factors:
  • Prolonged exposure to UV rays
  • Previous irradiation
  • Albinism and xeroderma pigmentosum
  • Long-standing skin irritation
  • Immunosuppression
• Gross appearance: ulcerated mass with raised, everted edges
• Microscopic appearance: groups of carcinoma cells infiltrating underlying tissue, with keratinization and epithelial pearls
• Spread: rapid infiltration, lymphatic spread to regional nodes, and blood stream spread
• Treatment: surgery or radiotherapy, with a safety margin of at least 0.5cm
• Differential diagnosis: keratoacanthoma, basal cell carcinoma, and malignant melanoma

Melanoma

• Incidence: increasing in western countries, rare before puberty
• Aetiology:
  • Prolonged exposure to UV rays
  • Benign naevus
  • Change in size, pigmentation, or bleeding
• Pathology and clinical types:
  • Superficial spreading melanoma (SSM)
  • Nodular melanoma (NMM)
  • Lentigo maligna (Hutchinson's melanotic freckle)
  • Acral-lentiginous melanoma
  • Amelanotic melanoma
• Prognostic factors:
  • Thickness of the lesion (Breslow classification)
  • Depth of invasion (Clark's level of invasion)
• Spread: direct, lymphatic, and blood stream
• Treatment: surgical excision with an adequate safety margin, sentinel lymph node biopsy, and chemotherapy for metastases
• Prognosis: 100% five-year survival rate if excised completely

This quiz covers the characteristics, incidence, and aetiology of Basal Cell Carcinoma, a locally malignant skin lesion commonly found in males over 40 years old.