Stage Information
Clark Classification (Level of Invasion)
TNM Definitions
Clinical Staging
AJCC stage groupings
Pathologic Staging
AJCC stage groupings
Agreement between pathologists in the histologic diagnosis of melanomas and
benign pigmented lesions has been studied and found to be considerably
variable. One such study found that there was discordance on the diagnosis of
melanoma versus benign lesions in 37 of 140 cases examined by a panel of
experienced dermatopathologists.[1] For the histologic classification of
cutaneous melanoma, the highest concordance was attained for Breslow thickness
and presence of ulceration, while the agreement was poor for other histologic
features such as Clark level of invasion, presence of regression, and
lymphocytic infiltration. In another study, 38% of cases examined by a panel
of expert pathologists had two or more discordant interpretations. These studies
convincingly show that distinguishing between benign pigmented lesions and
early melanoma can be difficult, and even experienced dermatopathologists can
have differing opinions. To reduce the possibility of misdiagnosis for an
individual patient, a second review by an independent qualified pathologist
should be considered.[2]
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 larger than 1.5 mm in
thickness and should always be reported. Accurate microstaging of the primary
tumor requires careful histologic evaluation of the entire specimen by an
experienced pathologist. Estimates of prognosis should be modified by sex and
anatomic site as well as by clinical and histologic evaluation.
Clark Classification (Level of Invasion)
- Level I: Lesions involving only the epidermis (in situ melanoma); not an invasive lesion.
- Level II: Invasion of the papillary dermis but 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.
The American Joint Committee on Cancer (AJCC) has designated staging by TNM
classification to define melanoma.[3]
TNM Definitions
Primary tumor (T)
- TX: Primary tumor cannot be assessed (e.g., shave biopsy or regressed melanoma)
- T0: No evidence of primary tumor
- Tis: Melanoma in situ
- T1: Tumor 1.0 mm or less in thickness with or without ulceration
- T1a: Tumor 1.0 mm or less in thickness and Clark level II or III with no ulceration
- T1b: Tumor 1.0 mm or less in thickness and Clark level IV or V or with ulceration
- T2: Tumor more than 1.0 mm but 2.0 mm or less in thickness with or without ulceration
- T2a: Tumor more than 1.0 mm but 2.0 mm or less in thickness with no ulceration
- T2b: Tumor more than 1.0 mm but 2.0 mm or less in thickness with ulceration
- T3: Tumor more than 2.0 mm but 4.0 mm or less in thickness with or without ulceration
- T3a: Tumor more than 2.0 mm but 4.0 mm or less in thickness without ulceration
- T3b: Tumor more than 2.0 mm but 4.0 mm or less in thickness with ulceration
- T4: Tumor more than 4.0 mm in thickness with or without ulceration
- T4a: Tumor more than 4.0 mm in thickness without ulceration
- T4b: Tumor more than 4.0 mm in thickness with ulceration
Regional lymph nodes (N)
Distant Metastasis (M)
- MX: Distant metastasis cannot be assessed
- M0: No distant metastasis
- M1: Distant metastasis
- M1a: Metastasis to skin, subcutaneous tissues, or distant lymph nodes
- M1b: Metastasis to lung
- M1c: Metastasis to all other visceral sites or distant
metastasis at any site associated with an elevated serum lactic dehydrogenase
Clinical Staging
Clinical staging includes microstaging of the primary melanoma and clinical
and/or radiologic evaluation for metastases. By
convention, it should be assigned after complete excision of the primary melanoma with clinical assessment for regional and
distant metastases.[3]
AJCC stage groupings
Stage 0
Stage IA
Stage IB
Stage IIA
Stage IIB
Stage IIC
Stage III
- Any T, N1, M0
- Any T, N2, M0
- Any T, N3, M0
Stage IV
Pathologic Staging
With the exception of clinical stage 0 or stage IA patients (who have a low
risk of lymphatic involvement and do not require pathologic evaluation of their
lymph nodes), pathologic staging includes microstaging of the primary melanoma
and pathologic information about the regional lymph nodes after sentinel node
biopsy and, if indicated, complete lymphadenectomy.[3]
AJCC stage groupings
Stage 0
Stage IA
Stage IB
Stage IIA
Stage IIB
Stage IIC
Stage IIIA
- T1–4a, N1a, M0
- T1–4a, N2a, M0
Stage IIIB
- T1–4b, N1a, M0
- T1–4b, N2a, M0
- T1–4a, N1b, M0
- T1–4a, N2b, M0
- T1–4a/b, N2c, M0
Stage IIIC
- T1–4b, N1b, M0
- T1–4b, N2b, M0
- T1–4b, N2c, M0
- Any T, N3, M0
Stage IV
References
-
Corona R, Mele A, Amini M, et al.: Interobserver variability on the histopathologic diagnosis of cutaneous melanoma and other pigmented skin lesions. J Clin Oncol 14 (4): 1218-23, 1996.
[PUBMED Abstract]
-
Farmer ER, Gonin R, Hanna MP: Discordance in the histopathologic diagnosis of melanoma and melanocytic nevi between expert pathologists. Hum Pathol 27 (6): 528-31, 1996.
[PUBMED Abstract]
-
Melanoma of the skin. In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 209-220.
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