Merkel cell carcinoma (MCC) typically appears as a rapidly growing, painless, firm bump or nodule on the skin. Its color can range from skin-colored to red, purple, pink, or bluish-red. The lesion is often dome-shaped or raised and may look shiny or pearly. MCC most commonly occurs on sun-exposed areas such as the face, head, neck, arms, and eyelids, but it can develop anywhere on the body, including less sun-exposed areas

. Key visual characteristics of Merkel cell carcinoma include:

• A firm, dome-shaped or raised lump that is usually painless

• Color variations including pink, red, purple, or bluish-red

• Rapid growth over weeks to months

• Sometimes it resembles other skin conditions such as a sore, insect bite, cyst, stye, wart, or pimple, which can lead to misdiagnosis

• The surface of the lesion may be smooth with visible enlarged blood vessels, unlike common warts

• It may ulcerate or bleed in some cases, especially if the skin breaks down over the tumor

• Nearby lymph nodes may become enlarged if the cancer has spread

The mnemonic AEIOU summarizes common features of MCC lesions: Asymptomatic (painless), Expanding rapidly, Immunosuppressed patient, Older than 50 years, and UV-exposed site on fair skin

. In summary, Merkel cell carcinoma looks like a fast-growing, painless, firm bump or nodule that is often red, purple, or skin-colored, frequently appearing on sun-exposed skin and sometimes mistaken for benign skin lesions