Cutaneous squamous cell carcinoma
Definition & Origin
- Malignant epithelial tumor originating from the keratinocytes of the epidermis.
- Most frequent mutations: Typical mutations are TP53 + NOTCH with RAS pathway activation.
- Pathogenesis: chronic UV exposure → cumulative DNA damage → Actinic Keratosis → carcinoma in situ (Bowen's disease) → invasive cSCC.
Risk Factors — High-Risk Criteria (DDG S3 Guideline 032-022OL)
Tumor-related
- High-risk is defined as TD > 6 mm + Ø > 2 cm plus desmoplasia and perineural invasion.
- Location: High-risk areas are lower lip + ear with high metastatic risk.
- High-risk criteria at a glance: the triad regularly asked for is tumour thickness / vertical depth of invasion, horizontal diameter and degree of differentiation; added to these are desmoplasia, perineural invasion, site, recurrence and immunosuppression.
| Criterion | High risk from |
|---|---|
| Vertical tumour thickness / depth of invasion | > 6 mm, or invasion beyond the subcutaneous fat (muscle, cartilage, bone) |
| Horizontal diameter | > 2 cm |
| Degree of differentiation (grading) | G3/G4 — poorly differentiated to undifferentiated |
| Desmoplasia | present — markedly increased risk of local recurrence and metastasis |
| Perineural invasion (PNI) | present, especially with nerve calibre ≥ 0.1 mm |
| Site | ear and lip, other high-risk facial areas |
| Recurrence | recurrent tumour after previous treatment |
| Host factor | immunosuppression (organ transplantation, haematological neoplasia, HIV) |
Patient-related
- Immunosuppression: History of organ transplantation (OTX), HIV, hematological diseases — risk increased 65–250-fold.
- Genodermatoses: Xeroderma pigmentosum, EB dystrophica.
- Muir-Torre Syndrome: Characteristic are sebaceous gland tumors + KA + visceral tumors as a variant of Lynch syndrome (MMR mutation).
Differential diagnoses
- Basal cell carcinoma
- Keratoacanthoma
- Dermatofibroma
- Pyogenic granuloma
- Arterial (ischaemic) ulcer
- Martorell Ulcer
- Actinic keratosis
- Cornu cutaneum
Practise Cutaneous squamous cell carcinoma in the app
Flashcards with spaced repetition, exam questions and spot-the-diagnosis on this topic – in DermaFuchs, free of charge.
In the DermaFuchs app: 26 flashcards · 10 clinical images
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More skin tumours
- Basal cell carcinoma
- Melanoma
- Lentigo maligna
- Actinic keratosis
- Actinic cheilitis
- Merkel cell carcinoma
- Microcystic adnexal carcinoma
- Dermatofibroma
Note: This page is intended for medical education and does not replace diagnosis or treatment decisions in individual cases. Treatment and follow-up content is available in the app.