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D36 Dermatology
Malignant Skin Tumours
Toronto Notes 2019
Does this Patient have a Mole or Melanoma?
ABCDE checklist
Asymmetry
Border (irregular and/or indistinct)
Colour (varied)
Diameter (increasing or >6 mm) Enlargement, elevation, evolution (i.e. change in colour, size, or shape)
Sensitivity 92% (CI 82-96%) Specificity 100% (CI 54-100%)
JAMA 1998;279:696-701
Malignant Melanoma
Clinical Presentation
• malignantcharacteristicsofamole:“ABCDE”mnemonic • sites:skin,mucousmembranes,eyes,CNS
Clinical Subtypes of Malignant Melanoma
• lentigomaligna
■ malignant melanoma in situ (normal and malignant melanocytes confined to the epidermis) ■ 2-6 cm, tan/brown/black uniformly flat macule or patch with irregular borders
■ lesion grows radially and produces complex colours
■ often seen in the elderly
■ 10% evolve to lentigo maligna melanoma
• lentigomalignamelanoma(15%ofallmelanomas)
■ malignant melanocytes invading into the dermis
■ associated with pre-existing solar lentigo, not pre-existing nevi
■ flat, brown, stain-like, gradually enlarging with loss of skin surface markings
■ with time, colour changes from uniform brown to dark brown with black and blue
■ found on all skin surfaces, especially those often exposed to sun, such as the face and hands
• superficialspreadingmelanoma(60-70%ofallmelanomas)
■ atypical melanocytes initially spread laterally in epidermis then invade the dermis
■ irregular, indurated, enlarging plaques with red/white/blue discolouration, focal papules or nodules ■ ulcerate and bleed with growth
• nodularmelanoma(30%ofallmelanomas)
■ atypical melanocytes that initially grow vertically with little lateral spread
■ uniformly ulcerated, blue-black, and sharply delineated plaque or nodule
■ rapidly fatal
■ may be pink or have no colour at all, this is called an amelanotic melanoma ■ “EFG” elevated, firm, growing
• acrallentiginousmelanoma(5%ofallmelanomas)
■ ill-defined dark brown, blue-black macule
■ palmar, plantar, subungual skin
■ melanomas on mucous membranes have poor prognosis
Pathophysiology
• malignantneoplasmofpigment-formingcells(melanocytesandnevuscells)
Epidemiology
• incidence:1/75(Canada),1/50(US)
• riskfactors:numerousmoles,fairskin,redhair,positivepersonal/familyhistory,1largecongenital
nevus (>20 cm), familial dysplastic nevus syndrome, any dysplastic nevi, immunosuppression, >50
common nevi, and sun exposure with sunburns, tanning beds
• mostcommonsites:back(M),calves(F)
• worseprognosisif:male,onscalp,hands,feet,latelesion,nopre-existingnevuspresent
Differential Diagnosis
• benign:nevi,solarlentigo,seborrheickeratosis • malignant:pigmentedBCC
Management
• excisionalbiopsypreferable,otherwiseincisionalbiopsy
• removefulldepthofdermisandextendbeyondedgesoflesiononlyafterhistologicdiagnosis
• bewareoflesionsthatregress–tumourisusuallydeeperthananticipated
• high dose IFN for stage II (regional), chemotherapy (cis-platinum, BCG) and high dose IFN for stage
III (distant) disease
• newerchemotherapeutic,genetherapies,andvaccinesstartingtobeusedinmetastaticmelanoma • radiotherapymaybeusedasadjunctivetreatment
Table 21. American Joint Committee on Cancer Staging System Based on Breslow’s Thickness of Invasion
Risk Factors for Melanoma
noSPFisaSIN
Sun exposure
Pigment traits (blue eyes, fair/red hair, pale complexion)
Freckling
Skin reaction to sunlight (increased incidence of sunburn)
Immunosuppressive states (e.g. renal transplantation)
Nevi (dysplastic nevi; increased number of benign melanocytic nevi)
Node Dissection for Lesions
>1 mm thick OR <1 mm and ulcerated OR >1 mitoses/mm2 (Stage IB or higher melanoma patients should be offered a sentinel lymph node biopsy)
• Assess sentinel node at time of wide excision
Tumour Depth
T1 <1.0 mm T2 1.01-2.0 mm T3 2.01-4.0 mm T4 >4.0 mm
Stage
Stage I T1a – T2a Stage II T2b – T4b Stage III any nodes Stage IV any mets
Approximate 5 Yr Survival
5-yr survival 90% 5-yr survival 70% 5-yr survival 45% 5-yr survival 10%
a = no ulceration; b = ulceration