Squamous Cell Carcinoma (SCC) of the Skin

Snapshot

• A 70-year-old man presents to the dermatologist’s office for his annual skin exam. He complains of a large pink lesion on his cheek that oozes and bleeds. It never seemed to heal properly. He is concerned, because he knows that he should have used more sunscreen throughout his life.

Introduction

• Invasive primary skin malignancy arising from keratinocytes of skin or mucosa
• Epidemiology
  • common in fair-skinned individuals
  • common in elderly patients
  • 2^nd most common form of skin cancer (first is basal cell carcinoma )
  • risk factors
    • sun exposure  
    • actinic keratosis 
    • immunosuppression (similar to treatment after organ transplant)
    • arsenic exposure
    • old scars or burns  
    • xeroderma pigmentosum
    • ionizing radiation
• Pathogenesis
  • damage to keratinocytes
  • metastases are rare
• Keratoacanthoma is a variant of low-grade squamous cell carcinoma
• grows rapidly and regresses spontaneously

Presentation

• Symptoms
  • typically asymptomatic
• Physical exam
  • red, poorly defined base with adherent yellow or white scale
  • smooth, dull, red, dome-shaped nodule with ulcerated center
  • frequently on sun-exposed areas
    • face, neck, hands, ears
    • common on lower lips
• lesions often against a background of sun-damaged skin

Evaluation

• Diagnosis by skin biopsy 
  • atypical keratinocytes and malignant cells
  • invasion into dermis
• keratin “pearls” on histology 

Differential Diagnosis

• Actinic keratosis
• Actinic cheilitis

Treatment

• Surgical
• wide local excision with negative margins

Prognosis, Prevention, and Complications

• Prognosis
  • if treated, very excellent prognosis
• Prevention
  • sun avoidance
  • sunscreen use