Clark's level is astaging system, which describes the level of anatomical invasion of themelanoma in the skin. It was developed byWallace H. Clark Jr. atHarvard University andMassachusetts General Hospital in the 1960s.

Five anatomical levels are recognized, and higher levels have worsening prognostic implications. These levels are:^[1]

• Level 1: Melanoma confined to theepidermis (melanoma in situ)
• Level 2: Invasion into thepapillary dermis
• Level 3: Invasion to the junction of thepapillary andreticular dermis
• Level 4: Invasion into thereticular dermis
• Level 5: Invasion into subcutaneous tissue.

In theUnited States, the current staging system adopted by theAmerican Joint Committee on Cancer (AJCC) no longer considers Clark's level, because it is less prognostic and more subjective than other alternatives.^[2]

However, it is a mandatory component for melanoma pathology inSweden.^[3]

• Staging of melanomas
• Breslow's depth

• Melanoma Staging Systems. National Cancer Institute. A resource on Clark's levels and Breslow's depth.
• Original article from Breslow. Cancer res, 1969.

• Histopathology
• Melanocytic nevi and neoplasms
• Dermatologic terminology
• Cancer staging

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