cSCC Staging Guide — DerMate.app

Purpose

Assigns the T category of a primary invasive cSCC under the two systems recommended by the European (EADO/EDF/EORTC) guideline, to identify tumours at higher risk of local recurrence, nodal metastasis and disease-specific death.

Population

Invasive primary cSCC. AJCC 8th edition T categories formally apply to head and neck cSCC (UICC 8th/9th edition uses the same criteria for other sites, excluding eyelid, perianal, vulva and penis); BWH applies to any site.

Criteria

AJCC: diameter (≤ 2 / > 2–4 / > 4 cm), deep invasion (> 6 mm or beyond subcutaneous fat), PNI, bone invasion. BWH: count of 4 risk factors — diameter ≥ 2 cm, poorly differentiated, PNI ≥ 0.1 mm, invasion beyond fat (bone invasion = T3).

High-risk categories

AJCC8 T3/T4 and BWH T2b/T3 define higher-risk cSCC (nodal imaging, multidisciplinary discussion, consideration of adjuvant RT). BWH T2b with 3 factors carries 2–4× the risk of T2b with 2 factors (Ran 2025).

📏 Tumour characteristics

Greatest clinical diameter (cm)

AJCC: ≤ 2 cm T1 · > 2 to 4 cm T2 · > 4 cm T3. BWH risk factor: ≥ 2 cm.

Histology / depth

Invasion beyond subcutaneous fatAJCC deep invasion (T3) · BWH risk factor Tumour thickness > 6 mmMeasured from the granular layer of adjacent normal epidermis to the base of the tumour. AJCC deep invasion (T3) Poorly differentiated histologyBWH risk factor (not part of AJCC T)

Perineural invasion (PNI)

PNI of nerve(s) ≥ 0.1 mm in calibreAJCC T3 · BWH risk factor PNI of a nerve lying deeper than the dermis, or clinical/radiographic involvement of named nerves (without skull base invasion)AJCC T3 only (any calibre)

Bone invasion

T category

AJCC 8th edition

—

BWH

—

Risk category —

AJCC stage group if N0 M0 —

💡

5-year cumulative incidence by number of BWH risk factors (Ran et al., 2025)

BWH factors	Local recurrence	Nodal metastasis	Distant metastasis	Disease-specific death
0 (T1)	1.7 %	0.6 %	0.2 %	0.3 %
1 (T2a)	5.0 %	3.6 %	1.1 %	1.9 %
2 (T2b)	8.8 %	11 %	2.4 %	5.4 %
3 (T2b)	16 %	20 %	7.9 %	11 %
4 (T3)	33 %	28 %	8.4 %	25 %

📋 T category definitions — reference

AJCC 8 (UICC 8/9)

T1 ≤ 2 cm in greatest dimension
T2 > 2 cm and ≤ 4 cm
T3 > 4 cm, or minor bone erosion, or PNI, or deep invasion (beyond subcutaneous fat or > 6 mm)
T4a gross cortical bone and/or marrow invasion
T4b skull base invasion and/or skull base foramen involvement
UICC differs: a tumour of exactly 2 cm is T2; UICC 9 (2026) also counts PNI of ≥ 5 nerves per section.

BWH

Risk factors: diameter ≥ 2 cm · poorly differentiated histology · PNI of nerve(s) ≥ 0.1 mm · invasion beyond subcutaneous fat
T1 0 factors
T2a 1 factor
T2b 2–3 factors
T3 4 factors or bone invasion
No N/M classification. T2b/T3 = high-stage.

ℹ️ Other prognostic factors not captured by T category (EADO guideline Box 4): location on lip/ear/temple, desmoplasia, lymphovascular invasion, immunosuppression, positive margins, recurrence. Consider them when judging overall risk.

📚 References

Stratigos AJ, Garbe C, Dessinioti C, et al. European consensus-based interdisciplinary guideline for invasive cutaneous squamous cell carcinoma. Part 1: diagnostics and prevention — update 2023. Eur J Cancer. 2023;193:113251.
Stratigos AJ, Dessinioti C, Garbe C, et al. European consensus-based interdisciplinary guideline for invasive cutaneous squamous cell carcinoma. Part 1: diagnostics and prevention — update 2026. Eur J Cancer. 2026 (in press).
Amin MB, Edge SB, Greene FL, et al., eds. AJCC Cancer Staging Manual. 8th ed. Springer; 2017 (Cutaneous squamous cell carcinoma of the head and neck).
Jambusaria-Pahlajani A, Kanetsky PA, Karia PS, et al. Evaluation of AJCC tumor staging for cutaneous squamous cell carcinoma and a proposed alternative tumor staging system. JAMA Dermatol. 2013;149(4):402–10.
Karia PS, Jambusaria-Pahlajani A, Harrington DP, Murphy GF, Qureshi AA, Schmults CD. Evaluation of American Joint Committee on Cancer, International Union Against Cancer, and Brigham and Women's Hospital tumor staging for cutaneous squamous cell carcinoma. J Clin Oncol. 2014;32(4):327–34.
Ruiz ES, Karia PS, Besaw R, Schmults CD. Performance of the American Joint Committee on Cancer Staging Manual, 8th edition vs the Brigham and Women's Hospital tumor classification system for cutaneous squamous cell carcinoma. JAMA Dermatol. 2019;155(7):819–25.
Ran NA, Granger EE, Brodland DG, et al. Risk factor number and recurrence, metastasis, and disease-related death in cutaneous squamous cell carcinoma. JAMA Dermatol. 2025;161(6):597–604.

Clinical decision support only. This tool is intended to assist clinical assessment and does not replace professional judgment. Always interpret results in the context of the individual patient.