What are common skin lesions?

Common Skin Lesions

The most common skin lesions include basal cell carcinoma, squamous cell carcinoma, melanoma, actinic keratoses, seborrheic keratoses, and benign nevi (moles), with malignant lesions accounting for approximately half of all skin growths requiring excision in older adults. 1

Malignant Skin Lesions

Basal Cell Carcinoma

• Most common type of skin cancer (4-5 times more common than squamous cell carcinoma) 2
• Accounts for approximately 80% of all malignant skin tumors 1
• Characteristics:
  • Pearly or waxy appearance
  • Rolled borders
  • Central depression or ulceration
  • Telangiectasias (visible small blood vessels)
  • Slow-growing
  • Rarely metastasizes but can cause substantial local destruction and disfigurement 2

Squamous Cell Carcinoma

• Second most common skin cancer
• Characteristics:
  • Firm, red, scaly or crusty lesions
  • May develop from actinic keratoses
  • More likely to metastasize than basal cell carcinoma
  • Can produce substantial local destruction 2

Melanoma

• Accounts for about 1% of skin cancers but causes most skin cancer deaths 2
• Characteristics (ABCDE criteria) 2:
  • A: Asymmetry
  • B: Border irregularity
  • C: Color variation (heterogeneous)
  • D: Diameter greater than 6 mm
  • E: Evolution (recent change) 2
• The "ugly duckling" sign: a pigmented lesion that looks different from other moles on the patient 2
• Five-year survival ranges from 99.5% for localized disease to 31.9% for distant-stage disease 2

Precancerous Lesions

Actinic Keratoses

• Precursors to squamous cell carcinoma
• Progression rates to squamous cell carcinoma range from 0.025% to 16% 3
• Characteristics:
  • Rough, scaly patches on sun-exposed areas
  • Red, pink, or flesh-colored
  • May be easier to feel than see
  • Often multiple lesions
• Treatment options include:
  • Cryosurgery
  • Topical 5-fluorouracil
  • Topical imiquimod
  • Photodynamic therapy
  • Curettage and electrodessication 2, 4

Dysplastic Nevi (Atypical Moles)

• Indicate higher risk of melanoma
• Rarely transform into malignant melanoma 3
• Characteristics:
  • Irregular borders
  • Multiple colors
  • Diameter often >5 mm
  • Asymmetric appearance
• Management depends on degree of atypia 3

Benign Skin Lesions

Seborrheic Keratoses

• Very common benign epidermal growths
• Characteristics:
  • "Stuck-on" appearance
  • Waxy, scaly surface
  • Color ranges from light tan to black
  • May be mistaken for melanoma

Benign Nevi (Moles)

• Common melanocytic growths
• Characteristics:
  • Symmetrical
  • Regular borders
  • Uniform color
  • Usually <6 mm in diameter
  • Stable over time

Risk Factors for Skin Cancer

• UV radiation exposure (sun exposure, tanning beds) 2
• Fair skin, light-colored eyes, red or blond hair 2
• History of frequent sunburns
• Older age
• Male sex
• Immunosuppression (organ transplant recipients, HIV) 2
• Family history of skin cancer
• More than 50 moles 2

Clinical Evaluation

When evaluating skin lesions, clinicians should:

1. Note the location (sun-exposed areas have higher risk of malignancy)
2. Assess for malignant features:
   • Asymmetry
   • Border irregularity
   • Color variability
   • Diameter >6 mm
   • Evolution/change over time 2
3. Consider using dermatoscopy to improve diagnostic accuracy if trained in the technique 3
4. Perform biopsy of suspicious lesions 2

Important Clinical Pitfalls

1. Melanoma mimics: Melanoma can be phenotypically diverse and mimic benign nevi, seborrheic keratoses, pigmented basal cell carcinomas, hematomas, and vascular growths 2

2. Delayed diagnosis in darker skin types: Persons with darker skin color are often diagnosed at later stages when skin cancer is more difficult to treat 2

3. Missing acral lentiginous melanoma: This type occurs on palms, soles, and under nails and may be overlooked during examination

4. Relying solely on typical appearance: Some malignant lesions may present atypically; biopsy is often necessary for definitive diagnosis 5

5. Overlooking high-risk patients: Organ transplant recipients and immunosuppressed individuals require more vigilant monitoring as they develop more aggressive skin cancers 2

By recognizing these common skin lesions and their characteristics, clinicians can identify concerning lesions early, leading to better outcomes for patients with skin cancer.