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SQUAMOUS CELL CARCINOMA

Overview

  • Second most common skin cancer after BCC

  • Associated with chronic ultraviolet light exposure

  • Risk factors:

    • Fitzpatrick skin type​

    • Sun exposure

    • Carcinogen exposure - pesticides, arsenic, organic hydrocarbons

    • Viral infection - HPV and herpes simplex

    • Radiation

    • Immunosuppression

    • Chronic wound - burns, discoid lupus, fistula tract, osteomyelitis

    • Psoralen and ultraviolet A (PUVA) therapy for psoriasis

    • Premalignant lesions

      • Actinic ​keratosis

      • Bowen's disease

      • Leukoplakia

      • Keratoacanthoma

  • Presents as an indurated nodular keratinising or crusted tumour that may ulcerate or an ulcer without keratinisation

Overview

Prognostic factors

  • Site (in increasing order of metastatic risk)

    • Sun-exposed sites​

    • Lip

    • Ear

    • Non-sun-exposed sites (perineum, sacrum, foot, etc)

    • Areas of radiation or thermal injury, chronic draining sinuses, chronic ulcers, chronic inflammation, Bowen's disese

  • Diameter - higher risk if greater than 2cm​

  • Depth - higher risk if greater than 4mm in depth or extending to subcutaneous tissue

  • Histological differentiation - poorer prognosis with poorer differentiation, lymphatic or vascular invasion

  • Immunosuppression

  • Recurrent lesions

Prognostic factors
Types of SCC

Types of SCC

  • Verrucous

    • Exophytic and slow growing​

    • Common on palms and soles

    • Less likely to metastasise

  • Ulcerative​

    • Aggressive with raised borders and central ulceration​

    • Commonly metastasise to regional lymph nodes

  • Marjolin's ulcer​

    • Typically arise from chronic wounds​

    • Burn scars have a 2% lifetime malignant degeneration potential

    • Lymph node metastasis is common

  • Subungual​

    • Involving nailbed​

    • Erythema, swelling, localised pain, nodularity and ulceration

Treatment

Treatment

  • Complete removal of primary tumour is needed

  • "In transit" metastasis is possible

  • There is a tendency of metastasis to spread by lymph nodes

  • Surgical excision

    • Low risk - 4mm​ margin

    • High risk - 6mm margin

    • Mohs' micrographic surgery

  • Currettage and cautery​

    • For small (<1cm), well-differentiated, primary, slow-growing tumours arising from sun-exposed sites by experienced physicians​

    • Not appropriate for locally recurrent disease

  • Cryosurgery​

    • Small histologically confirmed SCC

    • ​Not appropriate for locally recurrent disease

  • Radiotherapy​

    • Short- and long-term cure rates that are comparable with other ​treatments

    • May be best treatment in advanced tumours where surgical morbidity would be unacceptably high

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