Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer that typically appears as a fast-growing, painless bump on sun-exposed areas of the skin such as the face, head, neck, arms, or eyelids. It often looks like a firm, dome- shaped or raised lump that can be pink, red, purple, or skin-colored. The surface may be smooth with visible enlarged blood vessels, distinguishing it from common warts or cysts. Sometimes, it may resemble a sore, insect bite, stye, or pimple, and can ulcerate or bleed as it progresses

. Key visual features of Merkel cell carcinoma include:

• A solitary, painless, firm nodule or lump
• Color ranging from pink, red, purple to skin-colored
• Smooth or slightly scaly surface with possible overlying telangiectasia (visible blood vessels)
• Rapid growth over weeks to months
• Possible ulceration or bleeding in advanced lesions
• Often mistaken for benign lesions like cysts, styes, or insect bites
• May be accompanied by enlarged lymph nodes nearby due to spread

The mnemonic "AEIOU" helps identify MCC characteristics: Asymptomatic (painless), Expanding rapidly, Immunosuppressed patient, Older than 50 years, and UV-exposed skin site

. Because MCC can look quite variable and mimic other skin conditions, any new, rapidly growing, painless bump or sore on sun-exposed skin should be evaluated by a dermatologist promptly for biopsy and diagnosis

. Early detection is critical due to MCC's aggressive nature and tendency to spread quickly. In summary, Merkel cell carcinoma typically appears as a fast- growing, painless, firm, dome-shaped bump that is pink, red, or purple, often on sun-exposed areas, sometimes resembling a sore or cyst, with smooth surface and visible blood vessels