Malignant Melanoma
Melanoma Overview
- Malignant melanoma has the highest skin cancer-related mortality (is the leading cause of death due to skin cancer). It is commonly cited as the 5th most common type of cancer in the US (but pay attention that this does not include squamous cell and basal cell carcinomas, however).
Subtypes of Melanoma
There are multiple types of melanoma:
- Superficial spreading melanoma (~ 65%)
- Acral-lentiginous melanoma (on the palms and soles (the plantar distal extremities) and underneath the nails (subungal), which account for ~ 75% of melanomas in blacks and ~ 50% in Asians.
- Nodular melanoma, the 2nd most common type of melanoma, overall.
- Lentigo maligna, in sun-damaged areas
- Amelanotic melanoma
- Spitzoid melanoma
- Desmplastic melanoma
- Pigment synthesizing (animal-type) melanoma (aka, melanocytoma)
Melanoma Characteristics (ABCDE criteria)
- Melanoma can be asymmetric and possess drastically different coloration on two sides; it can possess a highly irregular border; color variegation – zones of different colors; is typically greater than 6 mm; and it evolves over time. For reference, the median growth rate for a superficial spreading melanoma is ~ 0.12 mm per month. Rate of growth in melanomas: characteristics and associations of rapidly growing melanomas.
- Another consideration is is the ugly duckling sign, which means, if a mole stands out from the other of a patient's typical moles, have a higher suspicion of melanoma.
- The Glasgow 7-point checklist is a useful scoring system that can help guide melanoma evaluation.
- With melanoma evaluation, "When in doubt, refer it out!" to a dermatologist – they having imaging modalities and can biopsy when necessary.
Morbidity/Mortality
- Malignant melanoma has a high propensity for metastasis. Fortunately, ~ 95% of melanomas are identified prior to distant metastasis, however, when melanoma does metastasize, it can do so widely.
- Common distant sites (beyond the skin and regional subcutaneous tissue) are as follows:
- Lungs
- Liver (and other gastrointestinal organs, less commonly)
- Bone
- Central nervous system (brain, meninges, etc...)
Melanoma Staging (TNM)
- Primary Tumor (T)
- Thickness.
- Ulceration status.
- Example, T2a would be a 1 to 2 mm thickness primary tumor with NO ulceration.
- Regional lymph node involvement (N)
- Number of nodes.
- Distant Metastasis (M)
- Anatomic site.
- LDH level.
- Example, M1a(1) would be local metastasis with an elevated LDH level.
Image Reference
Malignant Melanoma