Cancer- BCC, SCC, Melanoma

Question 1

What does basal cell carcinoma arise from?

Answer 1

Basal keratinocytes

Question 2

What causes BCC?

+aetiological factors

Answer 2

UVR exposure, childhood exposure esp important
Mainly affects skin types I and II

Risk factors:
Immunosuppression
Environmental carcinogens
Trauma

Xeroderma pigmentosum
Oculocutaneous albinism

Question 3

Pathophysiology and characteristics of BCC

Answer 3

Epidermal keratinocyte DNA damaged by solar UV -> tumour suppressor genes mutated
Leads to growth into tumour

Slow growing (6 months ish), locally destructive, almost never metastasises

Question 4

What are the different types of BCC?

Answer 4

Nodular-
slow growing, shiny, pearly nodule with superficial telangietasia. Common on face

superficial-
Well demarcated and scaly plaques, larger, slightly raised. Slow growth over months

infiltrative-
Thickened yellowish plaques with widespread infiltration, poor definition

pigmented-
Brown, blue, or grey lesion which is either nodular or superficial. Common in darker skin, lowkey looks like melanoma

Question 5

How is BCC investigated?

Answer 5

Primary inspection and biopsy + histopathology

Question 6

How is BCC treated?

Answer 6

Wide excision for most

Mohs surgery for infiltrative ones

Superficial- cryotherapy, photodynamic therapy, topical imiquimod

In those that can’t tolerate surgery- targeted treatment ie vismodegib (hedgehog inhibitor)

Question 7

What is squamous cell carcinoma?

Answer 7

Malignant tumour that arises from supra-basal keratinocytes (the rest of them compared to BCC)

Moat common in immunosuppressed populations

Question 8

Aetiological factors of SCC

Answer 8

Lifetime UV exposure
May also arise from chronic leg ulcers, burns, or chronic lupus

Risk factors:
Environment carcinogens
Trauma

Genetic factors like skin type, XP, OA

Question 9

Presentation and characteristics of SCC

Answer 9

Locally invasive, faster growing than BCC (2 months)
Low risk of metastases but if it metastasises the prognosis is poor

Warty crusted lump, sun damaged skin
90%+ on head, neck, hands, forearms
Plus ear, lip, scalp
May be painful and bleed

Question 10

How is SCC treated?

Answer 10

Complete surgical excision (+biopsy) with wide margin

Topical treatment if smaller and non invasive

Question 11

In SCC, what is associated with poor prognosis?

Answer 11

20mm+ diameter and 4mm+ depth
Regular immunosuppressant use

Question 12

What is malignant melanoma

Answer 12

Proliferation of atypical melanocytes
Potential for dermal invasion and widespread metastases

Question 13

Aetiological factors of malignant melanoma

Answer 13

Age and family history but intermittent intense sun exposure

Fair skin, melanocytic naevi (moles), family history, immunosuppression

25% of cases arise from prexisting moles

BRAF mutation
XP, OA

Question 14

What are the types of melanoma

Answer 14

superficial spreading-
Large, flat, irregular
Common in trunk and limbs
Grows lateral before vertical

acral lentiginous MM
Arises on palm or under nail, usually late

lentigo maligna
Invasive, found on sun damaged face/scalp/neck

nodular MM
Most aggressive, occurs on varied sites but often trunk. Rapid growing, bleeds and ulcerates