Merkel Cell Tumor: A Mystery Beneath the Surface

Merkel cell carcinoma (MCC) is an aggressive skin condition that requires prompt diagnosis and management. It predominantly affects older adults and has a high propensity for recurrence and metastasis. The acronym AEIOU, which stands for asymptomatic, expanding rapidly, immunosuppression, older than 50 years, and UV radiation, is often used in the approach to diagnosis. We present a unique and intriguing case of a 70-year-old patient with a solitary and asymptomatic exophytic lesion on her right forearm that had been present for one year. She had not received any treatment or medical advice to date. Our case contributes to the literature on MCC, highlighting the variety of differential diagnoses that can occur in an atypical variety such as the one we are describing. We recall the relevance of the histopathological approach, emphasizing the crucial role of immunohistochemistry in the presumptive diagnosis of this entity.