Pathology
- Arises from epidermal cells that migrate to skin surface that form superifical keratinising squamous layer
- Full thickness epidermal atypia is seen (cf basal atypia only in solar keratoses)
- Tumour cells seen to extend in all directions into the deep dermis and subcutaneous fat
- Tumour may be well differentiated (with production of keratin), moderately differentiated or poorly differentiated
Approach
- Sit / kneel in front of patient in order to be at the same level as the face
- Examine as for any lump
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- Inspect
- May occur on any part of the face (usually sun-exposed areas)
- Appears vascular (red-brown)
- Raised and everted edge
- May be of considerable size >1cm
- May be erosion of surrounding architecture if the tumour is advanced
- May have central ulceration
- Palpate
- Regional cervical lymphadenopathy (amy be due to metastatses or secondary infection)
Completion
- Ask about predisposing factors
- Congenital: xeroderma pigementosum
- Acquired:
- sunlight, radiation
- carcinogens
- pre-existing skin lesions: solar keratosis, Bowen's disease (CIN: intra epidermal carcinoma presenting as a single brown-red irregular plaguq usually on trunk that increases in size and may progress to invasive SCC)
- infections (HPV 5,8)
- Immunosupporession
- Chronic cutaneous ulceration - chronic burns, chronic venous ulcers (Marjolin's ulcer)
- How lesion affects life
- Cosmetics
Differential diagnoses:
- Benign skin lesions
- Kerathoacanthoma
- Infected seborrheic wart
- Solar keratosis
- Pyogenic granuloma
- Malignant skin lesions
- Basal cell carcinoma
- Malignant melanoma (amelanotic)
Treatment
- Primary lesion
- Excision with 1cm margin
- Moh's staged chemosurgery with histological assessment of margins and electrodissection - for lesions of the eyelids, ears and nasolabial folds
- Radiotherapy - unresectable lesions
- Nodal spread
- Surgical block dissection - if palpable nodes / Marjolin's ulcers
- Radiotherapy