Merkel Cell Carcinoma - Risk Factors and Warning Signs

Key risk factors for Merkel cell carcinoma include:

  • age over 50 (the majority of patients are over age 70)
  • male gender
  • light skin color
  • Ultraviolet exposure from the sun or tanning beds, and
  • immune suppression.

Merkel cell carcinomas are usually curable when detected and treated at an early stage. But since they are often aggressive and can advance rapidly, early detection and removal are especially important. These tumors usually appear as firm, painless lesions or nodules on a sun-exposed area (about 48 percent of the time on the head and neck, and frequently on the eyelids). They are typically red, blue, purple or skin-colored and vary in size (but are most commonly less than 20 mm in diameter). The average size on detection is about the diameter of a dime (17 mm).

Merkel cell carcinoma, local recurrence, forehead (left). Merkel cell carcinoma, primary tumor, lower arm (right).

It is vital that you and your physician be on the lookout for such signs, and for any new or changing lesions on your skin, whether or not the new growth or change seems particularly dramatic. This is especially true if you have already had an MCC. Pay particular attention to any previously treated site, and if you spot anything suspicious, let your physician see it immediately.

Some physicians use the acronym “AEIOU” to summarize the combination of risk factors and warning signs that call for close scrutiny and aid in early recognition:

  • A: Asymptomatic/lack of tenderness
  • E: Expanding rapidly
  •  I: Immune suppression
  • O: Older than 50 years
  • U: Ultraviolet-exposed/fair skin

Medical Reviewer

Deborah S. Sarnoff, MD

Causes of Merkel
Cell Carcinoma
Stages of Merkel
Cell Carcinoma