Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer that typically appears as a fast-growing, painless lump or nodule on the skin, often in sun- exposed areas such as the face, head, neck, arms, or eyelids. It can look like a firm, dome-shaped, or slightly raised bump that may be pink, red, purple, or bluish-red in color. The lesion may sometimes resemble a sore, insect bite, cyst, stye, or pimple and can occasionally ulcerate or bleed as it grows

. Key visual characteristics of Merkel cell carcinoma include:

• A single, firm, dome-shaped or raised lump
• Color variations: pink, red, purple, or bluish-red
• Typically painless and asymptomatic at first
• Rapid growth over days to weeks
• May cause loss of eyelashes (madarosis) when on the eyelid
• Often located on sun-exposed skin, especially the head, neck, and upper extremities
• May be mistaken for benign lesions such as cysts or insect bites due to its appearance
• Sometimes accompanied by enlarged nearby lymph nodes if it has spread

The "AEIOU" acronym helps identify MCC features: Asymptomatic (painless), Expanding rapidly, Immunosuppression, Older than 50 years, and UV-exposed skin site. Most MCC cases exhibit three or more of these traits

. In summary, Merkel cell carcinoma looks like a rapidly enlarging, painless, firm, shiny or slightly scaly lump, often reddish or purplish, primarily on sun-exposed areas of the skin. Because it can resemble other common skin conditions, any new, changing, or unusual skin growths should be evaluated by a dermatologist promptly