Premalignant Epidermal Tumors

Overview: Premalignant Lesions - Danger Signs

• Precursors to invasive carcinoma (SCC > BCC).
• Etiology: Chronic UV exposure (main), HPV, arsenic, radiation, immunosuppression, chronic inflammation, genetic (XP).
• Monitor for malignant transformation.
• Danger Signs (Transformation):
  • Rapid ↑ in size
  • Ulceration, bleeding, crusting
  • Induration, nodularity
  • Persistent inflammation
  • Pain or tenderness
  • Color change

⭐ Bowen's disease (SCC in situ) has a 5-10% risk of progressing to invasive SCC if untreated.

Actinic Keratosis - Sun's Kiss

• Aka Solar Keratosis; most common premalignant skin lesion.
• Etiology: Chronic UV exposure (esp. UVB) → p53 mutations.
• Risk Factors: Fair skin (Fitzpatrick I/II), ↑age, male, immunosuppression, outdoor work.
• Clinical:
  • Ill-defined, erythematous, scaly papules/plaques (<1 cm).
  • "Sandpaper" texture.
  • Sun-exposed sites: face, bald scalp, ears, dorsum hands/forearms.
  • Variants: Hypertrophic, atrophic, pigmented, cutaneous horn.
• Progression: Risk of Squamous Cell Carcinoma (SCC) ~0.025-16% per lesion/year.

  ⭐ Multiple AKs indicate field cancerization, significantly increasing SCC risk.

• Diagnosis: Clinical; biopsy if suspicious (induration, pain, bleeding, rapid growth, >1 cm).
• Management:

![Multiple actinic keratoses on sun-exposed skin](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Dermatology_Skin_Tumors_Premalignant_Epidermal_Tumors/e469b712-5467-4c9e-b3ef-506c61362009.jpg)

• Prevention: Sunscreen, protective clothing. 📌 Mnemonic: "Sun's Kiss can turn Nasty (SCC)".

Bowen's & Erythroplasia - Red Alert

• Bowen's Disease (BD): SCC in situ (intraepidermal).

  • Etiology: HPV (esp. 16, 18), arsenic, UV, immunosuppression.
  • Clinical: Solitary, sharply defined, erythematous, scaly patch/plaque.
  • Histo: Full-thickness epidermal atypia, intact basement membrane.
  • Risk: ~3-5% to invasive SCC.
  • 📌 Mnemonic: Bowen's: Border sharp, Often HPV/arsenic, Whole epidermis atypical, Erythematous Nasty Scale.

• Erythroplasia of Queyrat (EQ): SCC in situ of glans/prepuce (BD variant).

  • Etiology: HPV (esp. 16), uncircumcised, poor hygiene.
  • Clinical: Well-defined, velvety, shiny, erythematous plaque.
  • Histo: Same as BD (full-thickness atypia).
  • Risk: Higher, ~10-33% to invasive SCC.
  • 📌 Mnemonic: EQ: Erythematous Queyrat (glans) plaque, HPV's mark.

⭐ Erythroplasia of Queyrat carries a significantly higher risk (10-33%) of progressing to invasive squamous cell carcinoma compared to cutaneous Bowen's disease (3-5%).

Other Precursors (Leukoplakia, etc.) - Rogues' Gallery

• Leukoplakia:
  • White patch/plaque, non-scrapable.
  • Oral: Associated with tobacco, alcohol, HPV. Vulval: VIN precursor.
  • Risk: Squamous Cell Carcinoma (SCC).
• Arsenical Keratosis:
  • Cause: Chronic arsenic exposure.
  • Appearance: Multiple, firm, yellowish, hyperkeratotic papules/plaques.
  • Sites: Palms, soles, trunk.
  • Risk: SCC, Basal Cell Carcinoma (BCC), Bowen's disease.
• Radiation Keratosis (Chronic Radiodermatitis):
  • Cause: Ionizing radiation; long latency (often >10 years).
  • Features: Atrophy, telangiectasia, hyper/hypopigmentation, keratotic papules.
  • Risk: SCC.
• Keratoacanthoma (KA):
  • Growth: Rapidly growing, dome-shaped nodule with central keratin plug. Sun-exposed areas.
  • Nature: Controversial; often self-regressing but frequently treated as well-differentiated SCC. 📌 KA = Keratin crater, Acts fast.

⭐ Proliferative Verrucous Leukoplakia (PVL) is a high-risk form of oral leukoplakia with a very high rate of malignant transformation to SCC (often >70%).

High‑Yield Points - ⚡ Biggest Takeaways

• Actinic Keratosis (AK): Most common premalignant lesion; UV-induced, sandpaper texture; risk of SCC.
• Bowen's Disease: SCC in situ; full-thickness atypia; associated with HPV, arsenic.
• Leukoplakia: White mucosal patch, non-scrapable; oral form has malignant potential.
• Keratoacanthoma (KA): Rapid growth, central keratin plug; often excised, mimics SCC.
• Arsenical Keratoses: Multiple palmar/plantar lesions from chronic arsenic; high SCC risk.
• Cutaneous Horn: Conical keratin; biopsy base to exclude underlying SCC or AK.