Melanoma
last authored: Sept 2009, David LaPierre
Introduction
Half of all melanomas arise in clinically normal skin, and 1/3 originate from pre-existing nevi.
Lifetime risk of a mole becoming melanoma is perhaps 1:3000 for women and 1:10,000 for men (Tsao et al, 2002).
Causes and Risk Factors
UV-B exposure, fair skin type, pre-existing nevus, congenital nevus
Pathophysiology
Types of melanoma include:
superficial spreading
acral lentiginous melanoma
lentigo maligna (Hutchinson's)
nodular
Signs and Symptoms
- history
- physical exam
History
A,B,C,Ds. Maintain high clinical suspicion. Don’t forget amelanotic melanoma.
Physical Exam
Diagnosis
If lesion small or in inconsequential area: excisional biopsy
If lesion large or in esthetically sensitive area (eyelid): punch biopsy
Biopsy confirms diagnosis but more importantly assesses depth (1° determinant of prognosis)
- lab investigations
- diagnostic imaging
Lab Investigations
Diagnostic Imaging
Stage and Grade
Differential Diagnosis
Treatments
Surgery
When determining surgical margins:
For thickness:
- in situ: 0.5 cm
- <1 mm: 1 cm
- 1.1-2.0 mm: 1-2 cm
- 2-4 mm: 2 cm
- >4mm: 2-3 cm
can dissect sentinel nodes with dye tracing and scintillography; good for prognosis; not clear data on benefit for survival.
Lesions ≤1 mm deep need wide local excision (WLE) alone. Deeper lesions which are clinically node-negative need WLE + sentinel LN biopsy, proceeding to formal LN
dissection ± parotidectomy only if SLN(s) are positive histologically.
Melanoma which is node-positive at presentation should be offered WLE with lymphadenectomy, but this is primarily for locoregional control and has limited bearing on overall survival.
Adjuvant treatment with α-interferon: survival benefit equivocal.
Consequences and Course
Clinical Vignette 1
A person takes this treatment for this reason due to concerns re: condition
This happens.
How do you respond?
Clinical Vignette 2
Additional Resources
Topic Development
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