Melanoma In Situ Versus Paget’s Disease

Malignant melanoma in situ (MIS) is characterized by an intraepidermal proliferation of cytologically atypical melanocytes, often disposed as single cells in a haphazard pattern. This “pagetoid” scatter of atypical melanocytes closely resembles Paget’s disease itself. In addition, several other epithelial neoplasms (benign and malignant) are characterized by prominent pagetoid scatter of cells within the epidermis. Histological features that help to distinguish these neoplasms will be discussed.