AKT · Dermatology/Malignant & pre-malignant

Squamous cell carcinoma

Malignancy of keratinocytes (UV/immunosuppression)

Overview

A malignancy of epidermal keratinocytes that, unlike BCC, CAN metastasise. Arises on sun-damaged skin (and from actinic keratoses/Bowen disease) or in immunosuppressed patients (transplant recipients). A rapidly growing, keratotic, tender or ulcerated nodule that needs the suspected-cancer pathway.

Recognise

An enlarging, indurated, keratotic or ulcerated nodule on sun-exposed skin (face, ears, lips, dorsal hands, scalp)
Often tender; may have a keratin horn or crust; grows faster than BCC
Higher-risk: lip/ear sites, immunosuppression, perineural invasion, poorly differentiated, >2 mm thick — these can metastasise (regional nodes)

Red flags

Rapidly growing, tender, ulcerated keratotic lesion; lip/ear sites; immunosuppressed patient → 2-week-wait referral; palpable regional nodes

Differentials & how to tell them apart

Basal cell carcinomapearly, slow, rolled edge, does NOT metastasise — SCC is keratotic, faster and can spread

Keratoacanthomarapidly grows over weeks with a central keratin crater then may regress — often treated as well-differentiated SCC

Actinic keratosis / Bowen diseasepre-malignant precursors (rough macule / scaly in-situ plaque); SCC is the invasive nodule that can develop from them

Viral wartbenign HPV lesion — but a non-healing keratotic lesion in older/immunosuppressed skin should be biopsied

Clinical image

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Squamous cell carcinoma — clinical imagesDermNet

Investigations

Dermoscopy + diagnostic/excision biopsy. 2-week-wait suspected-cancer referral. Examine regional lymph nodes; image/stage high-risk lesions.

Management

Surgical excision with adequate margins (2-week-wait referral)

1Refer on the 2-WEEK-WAIT suspected-cancer pathway (SCC can metastasise). Treat by surgical excision with adequate margins.Gate: Unlike BCC, SCC CAN metastasise → it uses the urgent suspected-cancer (2-week-wait) pathway, and high-risk lesions (lip/ear, immunosuppressed, thick/poorly-differentiated) need wider margins/Mohs and nodal assessment
2High-risk or incompletely excised → Mohs/radiotherapy + staging of regional nodes; transplant recipients → liaise re immunosuppression; advanced disease → MDT, systemic therapy.

Surgical excision — first-line — wide local excision with adequate margins (Mohs for high-risk sites)

Radiotherapy — when surgery is unsuitable, or adjuvant for high-risk disease

Reduce immunosuppression / specialist systemic therapy — transplant patients and advanced/metastatic disease

Key points

SCC is the skin cancer to fast-track. Transplant/immunosuppressed patients develop multiple aggressive SCCs. It arises from actinic keratoses and Bowen disease — the precursor lesions.

Monitor & prognosis

Regional nodes and surveillance for recurrence/new lesions.

Good when excised early; worse with high-risk features or metastasis.

Source: NICE NG12; BAD SCC guideline