The Clark level is determined by examining the melanoma under a microscope and identifying the deepest layer of the skin that the cancer has invaded. Here are the five levels:
Level I: The melanoma is confined to the epidermis (outermost layer of skin). Level II: The melanoma has invaded the papillary dermis (upper layer of the dermis). Level III: The melanoma has reached the junction of the papillary and reticular dermis. Level IV: The melanoma has invaded the reticular dermis (deeper layer of the dermis). Level V: The melanoma has invaded the subcutaneous tissue (beneath the skin).
