We report the case of a 64-year-old man with a plaque-like lesion on the lower back. Clinically, squamous cell carcinoma was suspected, but the histological features resembled those of isolated Darier's disease or pemphigus vegetans. The lesion was removed with the final diagnosis of acantholytic dyskeratotic acanthoma. We discuss this case with special regard to the differential diagnosis of other isolated acantholytic acanthomas.