What are Clark’s levels?

A system used to describe the depth of invasion of a melanoma that was originally described by Dr. Wallace H. Clark, Jr. The system provides a helpful means to determine the probability of developing progressive disease. Primary tumors are classified according to the degree of invasion into the various anatomic levels of the skin. This classification scheme has been shown to correlate well with 5-year survival rates; however, the new 2009 AJCC Melanoma Staging and Classification System, for the first time, has removed the Clark’s level as a recommended parameter.
• Level I: Tumor cells in epidermis only (melanoma in situ)
• Level II: Tumor cells extend from epidermis into (but do not fill) papillary dermis
• Level III: Tumor cells extend from epidermis into and fill papillary dermis
• Level IV: Tumor cells extend into reticular dermis
• Level V: Tumor cells extend through the dermis into underlying subcutaneous fat