Clark level
A histologic staging system for melanoma based on the anatomic level of invasion through skin layers.
Full Definition
The Clark level is a five-tier classification system developed by Wallace Clark Jr. to describe the depth of melanoma invasion through the layers of the skin. Level I indicates melanoma confined to the epidermis (in situ), Level II shows invasion into the papillary dermis, Level III fills the papillary dermis, Level IV invades the reticular dermis, and Level V penetrates into subcutaneous fat. While largely superseded by Breslow thickness measurements, Clark levels remain relevant in certain staging scenarios and continue to appear in pathology reports for comprehensive melanoma assessment.
Usage
Usage note: Use Roman numerals (I-V) when documenting Clark levels, not Arabic numerals.
In Context
- "The pathology report indicated a Clark level III melanoma with invasion filling the papillary dermis." — Pathology report
- "Clark level assessment complements Breslow thickness in melanoma staging protocols." — Clinical documentation