We present the case of a 40-year-old woman who had a flesh-colored asymptomatic plaque-like lesion above her chin since she was 30 years old. She was generally healthy and physical examination revealed no congenital abnormalities. Histopathology revealed a normal epidermal surface, mature striated muscle fibers arranged randomly within the dermis, and subcutaneous tissue associated with normal-appearing mesenchymal elements such as adipose tissue, collagen, blood vessels, and mature hair follicles. This fits the diagnosis of rhabdomyomatous mesenchymal hamartoma. Our case was different from previously reported cases with regards to the age of onset and clinical presentation. We report this rare adult case and discuss its differential diagnosis.