Last major update: November 2008 - next update November 2009
Revised: 22 September 2009
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.
● Used to define subcategories of T1 melanomas (1 mm or less in thickness) (J Natl Cancer Inst 1989;81:1893)
● NOT useful for melanoma of palm or sole
● Clark’s levels are related to incidence of nodal metastases but only consider primary tumor, not nodes or metastases
● Less prognostic significance than T classification (J Craniofac Surg 2007;18:1353)
● Less reproducible than Breslow’s system (J Pathol 1991;163:245); also not always uniform due to variation in depth of skin layers
● 5 year disease free survival is 100% with level II, 88% with level III, 66% with level IV, 15% with level V
● Must recognize that deep collection of malignant melanocytes may be attached to a pilosebaceous unit
● I: not penetrating basement membrane (in situ)
● II: in papillary dermis (difficult to differentiate II versus III (SEER)
● III: filling and expanding the papillary dermis and stopping at the interphase between the papillary and reticular dermis
● IV: in the reticular dermis
● V: in the subcutaneous tissue
Diagram of skin layers Clark’s levels
End of Skin-Melanocytic Tumors > Clark’s levels of invasion
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