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D34 Dermatology
Malignant Skin Tumours
Toronto Notes 2019
Workup/Investigations of BCC and Other NMSCs
• History: duration, growth rate, family/
personal Hx of skin cancer, prior therapy to
the lesion
• Physical: location, size, whether
circumscribed, tethering to deep structures,
full skin exam, lymph node exam
• Biopsy: if shallow lesion, can do shave
biopsy; otherwise punch or excisional biopsy may be more appropriate
Surgical Margins
• Smaller lesions: electrodessication and
curettage with 2-3 mm margin of normal
skin
• Deep infiltrative lesions: surgical excision
with 3-5 mm margins beyond visible and palpable tumour border, which may require skin graft or flap; or Mohs surgery, which conserves tissue and does not require margin control
Malignant Skin Tumours
Non-Melanoma Skin Cancers
BASAL CELL CARCINOMA
Subtypes
• noduloulcerative(typical)
■ skin-coloured papule/nodule with rolled, translucent (“pearly”) telangiectatic border, and
depressed/eroded/ulcerated centre • pigmentedvariant
■ flecks of pigment in translucent lesion with surface telangiectasia
■ may mimic malignant melanoma • superficialvariant
■ flat, tan to red-brown plaque, often with scaly, pearly border, and fine telangiectasia at margin
■ least aggressive subtype
• sclerosing(morpheaform)variant
■ flesh/yellowish-coloured, shiny papule/plaque with indistinct borders, indurated
Pathophysiology
• malignantproliferationofbasalkeratinocytesoftheepidermis
■ low grade cutaneous malignancy, locally aggressive (primarily tangential growth), rarely metastatic ■ usually due to UVB light exposure, therefore >80% on face
■ may also occur in previous scars, radiation, trauma, arsenic exposure, or genetic predisposition
(Gorlin syndrome)
Epidemiology
• mostcommonmalignancyinhumans
• 75% of all malignant skin tumours >40 yr, increased prevalence in the elderly
• M>F,skinphototypesIandII,chroniccumulativesunexposure,ionizingradiation,
immunosuppression, arsenic exposure
Differential Diagnosis
• benign:sebaceoushyperplasia,intradermalmelanocyticnevus,dermatofibroma • malignant:nodularmalignantmelanoma,SCC
Management
• imiquimod5%cream(Aldara®)orcryotherapyisindicatedforsuperficialBCCsonthetrunk • fluorouracilandphotodynamictherapycanalsobeusedforsuperficialBCCs
• shave excision and electrodessication and curettage for most types of BCCs, not including
morpheaform
• Mohssurgery:microscopicallycontrolled,minimallyinvasive,stepwiseexcisionforlesionsontheface
or in areas that are difficult to reconstruct
• radiotherapyusedinadvancedcasesofBCC
• vismodegib is approved for metastatic BCC, also in syndromes characterized by multiple BCCs (Gorlin
Syndrome)
• follow-upfornewprimarydiseaseorrecurrence
• 95%curerateiflesion<2cmindiameteroriftreatedearly
BOWEN’S DISEASE (SQUAMOUS CELL CARCINOMA IN SITU)
Clinical Presentation
• sharplydemarcatederythematouspatch/thinplaquewithscaleand/orcrusting • often1-3cmindiameterandfoundontheskinandmucousmembranes
• evolvestoSCCin10-20%ofcutaneouslesionsand>20%ofmucosallesions
Management
• sameasforBCC
• biopsyrequiredfordiagnosis
• topical5-fluorouracil(Efudex®)orimiquimod(Aldara®)usedifextensiveandasatooltoidentify
margins of poorly defined tumours
• cryosurgery
• shaveexcisionwithelectrodessicationandcurettage