Clark Levels for Cutaneous Malignant Melanoma

Clark described the invasion of a malignant melanoma based on the histologic levels of the skin and subcutaneous tissues.

Depth of Invasion	Clark Level
none (in situ, above the basement membrane)	I
into papillary dermis	II
at the interface between the papillary and reticular dermis with variable involvement of superficial reticular dermis	III
reticular dermis	IV
subcutaneous tissue	V

where:

• The reticular dermis is characterized by collagen bundles.

• Classification as level III would show interobserver variation.

• The depth of invasion in mm (Breslow depth) versus Clark level is affected by age, location, nutritional status and comorbid conditions..

from Figure 1, Wanebo et al (1975)

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Purpose: To determine the Clark level for a cutaneous malignant melanoma.