Skin & Soft Tissue: Keratoacanthoma (KA)

Basics

• Hyperkeratosis of Pilosebaceous Infundibulum
• Benign but Similar Appearance to Squamous Cell Carcinoma (SCC)

Presentation

• Rolled Edges
• Crater Filled with Keratin Plug
• Diameter 1-2 cm
• Stages:
  • Proliferation: Rapid Growth Over 6-8 Weeks
  • Maturation: Stable for Weeks-Months
  • Involution: Spontaneous Regression to an Atrophic Scar
• Most Common on Sun-Exposed Hear-Bearing Areas (Head, Neck & Extremities)

Diagnosis

• Difficult to Distinguish from Squamous Cell Carcinoma (SCC)
• True Diagnosis Requires Histologic Exam
  • Excisional Biopsy is Best

Treatment

• Primary Treatment: Excision (Rule Out SCC)
  • May Consider Electrodessication with Curettage if Small
• Consider Mohs Micrographic Surgery in Cosmetically Sensitive Areas
• Other Possible Options:
  • Topical Imiquimod
  • Topical 5-Fluorouracil (5-FU)
  • Intralesional 5-Fluorouracil (5-FU)
  • Intralesional Methotrexate