Squamous Cell Carcinoma

Question 1

In SCC, where do the mutations occur?

Answer 1

Squamous keratinocytes in the epidermis.

These squamous keratinocytes lie in the stratum spinosum (above the stratum basale).

Question 2

What strata does SCC affect?

Answer 2

Stratum spinosum

Question 3

What gene is often involved in SCC?

Answer 3

Mutations in p53 tumour suppressor gene

Question 4

Risk factors for SCC?

Answer 4

• UV
• Immunosuppression
• Fitzpatrick skin types I and II (fairer skin)
• Solid organ transplant recipients
• Increasing age
• Male sex
• Ionising radiation
• Sites of chronic inflammation

Question 5

What is the most common skin cancer in Fitzpatrick skin types V and VI (brown and black skin)?

Answer 5

SCC

Question 6

Morphology of a cutaneous SCC?

Answer 6

1) Firm to palpate (may be nodular/plaque-like)

2) May ulcerate and bleed

3) May be tender/painful

4) May have a crusty (keratotic) top with a nodular base

5) Size is variable

Question 7

What are the characteristic features of SCC lesions?

Answer 7

Bleeding, itching & crusting.

Lesions will typically appear in sun-exposed areas (e.g. lips, back of hands).

Question 8

What is Bowens disease?

Answer 8

Also known as SCC in situ

When cancerous cells are confined to the EPIDERMIS. Can progress into invasive SCC.

Question 9

What is actinic keratosis?

Answer 9

Formation of precancerous scaly lesions on the skin.

Question 10

What cancer can actinic keratosis develop into?

Answer 10

10% risk of developing into SCC

Question 11

Risk factors for actinic keratosis?

Answer 11

Same as SCC e.g. chronic UV exposure and Fitzpatrick skin types I and II

Question 12

1st line investigation in SCC?

Answer 12

Biopsy for histology

Question 13

What is biospy option is used if the SCC is small & accessible area?

Answer 13

Excisional or shave biopsy to remove the whole lesion

Question 14

What biopsy option is used if SCC is large, an inaccessible area, present in a cosmetically sensitive area etc?

Answer 14

Incisional/punch biopsy which samples only a small (usually 4mm) part of the lesion

Question 15

What staging is used to stage SCC?

Answer 15

TNM

Question 16

What are some high risk features of an SCC lesion?

Answer 16

• Size: >2mm deep or >20mm wide
• Site: face, ear, genitals, hands, feet
• Recurrence
• Immunosuppressed individual
• Poor differentiation (histologically)
• Perineural invasion (histologically)
• High tumour budding

Question 17

1st line mx of Bowen’s disease?

Answer 17

Destructive therapies e.g. cryotherapy or topical therapies like 5-fluorouracil

Question 18

What does cryotherapy involve?

Answer 18

A form of non-surgical destruction that commonly uses liquid nitrogen to freeze the skin lesion.

Question 19

What topical agent can be used in mx of Bowen’s disease?

Answer 19

5-fluorouracil

Question 20

Mx of invasive SCC (i.e. growing beyond the epidermis)?

Answer 20

Conventional surgical excision with a minimum of 4mm margins

Question 21

What surgery is indicated in SCC that is present in a cosmetically sensitive location like the face?

Answer 21

Mohs micrographic surgery (aka margin-controlled excision)

Question 22

Mx of metastatic SCC?

Answer 22

May consist of surgical excision, radiotherapy and chemotherapy

Question 23

What are margins in surgical excision of SCC <20mm in diameter?

Answer 23

4mm margins

Question 24

What are margins in surgical excision of SCC >20mm in diameter?

Answer 24

6mm margins

Question 25

What diameter of SCC gives a poorer prognosis?

Answer 25

> 20mm

Question 26

What depth of SCC gives a poorer prognosis?

Answer 26

> 4mm

Question 27

What depth of SCC gives a better prognosis?

Answer 27

<2mm