Squamous cell carcinoma of the skin

Question 1

Definition

Answer 1

squamous cell carcinoma second most common form of skin cancer, arising from the squamous cells in the epidermis of the skin.

Question 2

Assosciations

Answer 2

The development of SCC is typically linked to cumulative sun exposure and ultraviolet (UV) radiation.
Subsequent DNA damage and genetic mutations within the squamous cells result in uncontrolled cell growth and the formation of malignant tumours.

Question 3

Pre-cancerous form of cutaneous SCC

Answer 3

Actinic keratosis (solar keratosis), which arises due to sun damage also.

Question 4

Types of SCC

Answer 4

• Invasive (penetrating the basement membrane of the epidermis to invade the dermis) or in situ (Bowen’s disease).

Question 5

Types of invasive cutaneous SCC include

Answer 5

• Cutaneous horn: produced by excess keratin production
• Marjolin ulcer: cutaneous SCC, which develops within a scar or ulcer
• Keratoacanthoma: a rapidly developing keratinised nodule, which can resolve without treatment

Question 6

Epidemiology

Answer 6

• Incidence increases with age
• Fair skin, light hair, and light eye colour

Question 7

Risk factors

Answer 7

• Sun exposure and history of sunburns
• Use of tanning beds
• Chronic skin inflammation or injury
• Human papillomavirus (HPV) infection
• Immunosuppression

Question 8

Signs

Answer 8

• Scaly or erythematous lesions
• Crusted or indurated lesions
• Bleeding lesions
• Irregular borders

Question 9

Symptoms

Answer 9

Typically develop over weeks to months and can vary from several millimeters to centimeters in diameter.
- Itchy, tender or painful lesions
- Ulcerating lesions
- Lesions on sun-exposed areas, such as ears, face, forearms and lower legs.
- Asymptomatic

Question 10

Investigations

Answer 10

FIRST LINE:
- Dermoscopy: A non-invasive technique to evaluate skin lesions, used to identify features suggestive of SCC
- Skin biopsy : Definitive diagnosis is established by histopathological examination of a skin biopsy, which may include punch, shave, or excisional biopsy
- CT TAP: full CT scan for staging is indicated if there is suspicion of widespread metastases

Question 11

Treatment

Answer 11

Surgical excision: the mainstay of treatment for SCC is surgery.
- Wide local excision
- Mohs micrographic surgery = specialised technique with improved cure rates and tissue preservation, particularly useful for high-risk or recurrent tumours, and those located on cosmetically sensitive areas.
- Aggressive cryotherapy : may be offered for small, thin, low-risk tumours
- Topical 5-fluorouracil: A chemotherapy agent used in situ SCC (Bowen’s disease) when surgery is CI or declined.
- Imiquimod: An immune response modulator used for the treatment of in situ SCC (Bowen’s disease) when surgery is CI or declined.
- Radiotherapy: Indicated for inoperable or metastatic tumours, and as adjuvant therapy for high-risk or incompletely excised tumours.