Melanoma Treatment (PDQ®): Treatment - Health Professional Information [NCI]-Stage Information for Melanoma Clinical staging is based on whether the tumor has spread to regional lymph nodes or distant sites. For melanoma that is clinically confined to the primary site, the chance of lymph node or systemic metastases increases as the thickness and depth of local invasion increases, which worsens the prognosis. Melanoma can spread by local extension (through lymphatics) and/or by hematogenous routes to distant sites. Any organ may be involved by metastases, but lungs and liver are common sites.

The microstage of malignant melanoma is determined on histologic examination by the vertical thickness of the lesion in millimeters (Breslow classification) and/or the anatomic level of local invasion (Clark classification). The Breslow thickness is more reproducible and more accurately predicts subsequent behavior of malignant melanoma in lesions thicker than 1.5 mm and should always be reported.

Accurate microstaging of the primary tumor requires careful histologic evaluation of the entire specimen by an experienced pathologist.

Clark Classification (Level of Invasion)

Table 1. Clark Classification (Level of Invasion)

Level of Invasion	Description
Level I	Lesions involving only the epidermis (in situ melanoma); not an invasive lesion.
Level II	Invasion of the papillary dermis; does not reach the papillary-reticular dermal interface.
Level III	Invasion fills and expands the papillary dermis but does not penetrate the reticular dermis.
Level IV	Invasion into the reticular dermis but not into the subcutaneous tissue.
Level V	Invasion through the reticular dermis into the subcutaneous tissue.

American Joint Committee on Cancer (AJCC) Stage Groupings and TNM Definitions

Melanoma staging is defined by the AJCC's TNM classification system.[1]

Table 2. TNM Definitions for Stage 0 Melanoma

Stage	TNM	Description	Image
Clinicala
Pathologicalb
Stage 0 melanoma in situ.
	0	0	Tis	Melanomain situ
			N0	No regional metastases
			M0	No detectable evidence of distant metastases
T = primary tumor; N = regional lymph nodes; M = distant metastasis.
Adapted with permission from AJCC: Melanoma of the skin. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 325-44.
The explanations for superscripts a and b are at the end ofTable 7.

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