Pathology Cheat Sheet
Skin Tumours: Read the Architecture
Skin tumours for NEET-PG: squamous cell carcinoma keratin pearls, basal cell carcinoma palisading, melanoma ABCDE, Breslow thickness, and HMB-45 marker.
MedNext Academy | 3 min read
Skin Tumours: Read the Architecture
Skin tumours for NEET-PG: squamous cell carcinoma keratin pearls, basal cell carcinoma palisading, melanoma ABCDE, Breslow thickness, and HMB-45 marker.
The common tumours of the skin including squamous and basal cell carcinoma and melanoma.
High-yield lines
- Chronic ultraviolet exposure is the main risk factor for skin cancers.
- Squamous cell carcinoma of the skin arises from actinic keratosis and can metastasise.
- Squamous cell carcinoma shows keratin pearls and intercellular bridges.
- Basal cell carcinoma is the most common skin cancer and rarely metastasises.
- Basal cell carcinoma shows nests of basaloid cells with peripheral palisading and a pearly rolled border with telangiectasia.
- Melanoma is the most dangerous skin cancer and arises from melanocytes.
- The ABCDE criteria of asymmetry, border irregularity, colour variation, diameter, and evolution suggest melanoma.
- Breslow thickness is the most important prognostic factor in melanoma.
- Melanoma expresses S-100, HMB-45, and Melan-A on immunohistochemistry.
- The radial growth phase of melanoma precedes the vertical growth phase that determines metastatic risk.
- A benign naevus is symmetric and uniform, unlike the atypia and pagetoid spread of melanoma.
- Seborrhoeic keratosis is a common benign pigmented lesion with a stuck-on appearance and horn cysts.
Mapped competency codes
- PA34.1
- PA34.2
- PA34.3
- PA34.4
Continue into the full chapter
This summary maps to PA33-bone-and-soft-tissue.
Frequently Asked Questions
What is the most common skin cancer?
Basal cell carcinoma, which shows basaloid nests with peripheral palisading and a pearly rolled border, and rarely metastasises.
What is the most important prognostic factor in melanoma?
The Breslow thickness, the depth of tumour invasion measured in millimetres, which predicts metastatic risk and survival.
What are the ABCDE criteria for melanoma?
Asymmetry, border irregularity, colour variation, diameter greater than 6 mm, and evolution over time, which raise suspicion for melanoma.
Which markers confirm melanoma on immunohistochemistry?
S-100, HMB-45, and Melan-A, which identify the melanocytic origin of the tumour.
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