Precancerous skin lesions

Precancerous skin lesions refer to various dermatological growths that are at an increased risk of developing into skin cancer. Typical precancerous skin lesions include lentigo maligna, which may develop into malignant melanoma, and actinic keratosis, which may develop into squamous cell carcinoma. There is also a risk of leukoplakia – presenting in the oral cavity as white plaques – progressing to squamous cell carcinoma. Bowen disease and erythroplasia of Queyrat are less common types of precancerous skin lesions and are often associated with the human papillomavirus (HPV). To prevent malignant transformation, surgical excision is usually the treatment of choice.

• Definition: precancerous lesion with intraepithelial proliferation of dysplastic melanocytes
• Epidemiology: peak incidence between 70 and 79 years of age ^[1]
• Etiology: : exposure to UV light
• Lesion
  • Mostly found in areas exposed to sun (e.g., face, neck)
  • Darkly pigmented macule
  • Irregular borders and varying size
  • Gradual growth, color irregularities, surrounding island-like speckling
  • See “ABCDE criteria.”
• Pathology: clusters of spindled, atypical melanocytes
• Treatment: surgical excision with a safety margin
• Complications: may transform into lentigo maligna melanoma

• Definition: UV-induced precancerous skin lesion that may progress to skin cancer.
• Epidemiology: occurs especially in individuals with light skin who are over the age of 50
• Etiology: : sun exposure (e.g., from working outdoors)
• Lesion
  • Occurs on areas of sun-exposed skin
  • Initially: small lesion (papule or plaque) with rough surface (sandpaper-like texture)
  • Later: Lesions grow and become brown or erythematous and scaly.
• Special types
  • Actinic cheilitis: actinic keratosis on the lower lip ^[2]
  • Cutaneous horn
    • Benign growth composed of keratin that resembles a horn
    • May develop from preexisting actinic and seborrheic keratoses or warts
    • Can progress to squamous cell carcinoma (SCC)
    • Treatment of choice is surgical excision with a margin.
• Pathology
  • Atypical cells in the basal and squamous layers
  • Hyperkeratosis and parakeratosis
  • Granular layer is usually absent.
• Treatment ^[3]
  • Single lesions (defined as 1–5 lesions): cryotherapy with liquid nitrogen
  • Multiple lesions (defined as ≥ 6 lesions)
    • 5-fluorouracil, imiquimod
    • Photodynamic therapy
• Prognosis
  • Lesions may either regress, persist, or progress to squamous cell carcinoma (SCC).
  • The degree of epithelial dysplasia determines the risk of squamous cell carcinoma.
• Prevention: sunscreen ≥ SPF 30

• Definition: hyperkeratosis of the epithelium and mucous membranes ^[2][4][5]
• Etiology
  • Tobacco smoking
  • Alcohol consumption
• Lesion
  • Most commonly affects the oral cavity
  • Persistent white plaques that usually cannot be scraped off
• Diagnostics: suspicious plaques (i.e., indurated or ulcerated) should be biopsied and checked for dysplasia
• Pathology
  • Hyperkeratosis, parakeratosis, acanthosis, and/or epithelial atrophy
  • Low-grade dysplasia possible
• Differential diagnosis: oral hairy leukoplakia in immunocompromised individuals
• Treatment
  • Smoking cessation
  • Cryotherapy, laser ablation
  • If lesions persist: surgical excision
• Complications: may develop into squamous cell carcinoma

Although Bowen disease affects the skin and erythroplasia of Queyrat affects the mucous membrane, the precancerous lesions are histopathologically identical.

Bowen disease

• Definition: squamous cell carcinoma in situ (SCCIS) of the skin
• Etiology
  • Exposure to sun
  • Often associated with human papillomavirus (HPV) types 16 and 18
  • May be related to arsenic exposure
• Lesion
  • Commonly occurs on skin that is exposed to sun
  • Irregularly shaped and sharply defined borders
  • Erythematous and scaly
• Diagnostics: biopsy (confirmatory test)
• Treatment
  • Pharmacotherapy (e.g., 5-FU, imiquimod)
  • Photodynamic therapy
  • Surgical excision with a margin
• Prognosis
  • May progress to invasive squamous cell carcinoma
  • Excellent prognosis if treated

Erythroplasia of Queyrat (Bowen disease of the glans penis)

• Definition: squamous cell carcinoma in situ (SCCIS) of the penile mucosa
• Etiology
  • Chronic irritation or infection
  • Lack of circumcision
  • HPV types 16 and 18
• Lesion
  • Most commonly preputium and glans penis affected
  • Single or multiple sharply demarcated, nonhealing lesions (e.g., plaques, red papules)
  • May ulcerate and bleed easily
• Treatment and prognosis: see Bowen disease

• See “Bowenoid papulosis.”