Squamous Cell Carcinoma
- Malignant tumor of epithelial cell keratinocytes (skin and mucus membranes)
- Second most common skin cancer
- 20% of all cutaneous malignancies
- Risk for metastasis greater than for BCC
Clinical Features
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Invasive SCCs are usually slowly-growing, tender, scaly or crusted lumps.
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The lesions may develop sores or ulcers that fail to heal.
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Most SCCs are found on sun-exposed sites, particularly the face, lips, ears, hands, forearms and lower legs.
- SCC lesions vary in size from a few millimeters to several centimeters in diameter.
- Sometimes they grow to the size of a pea or larger in a few weeks
- But more commonly they grow slowly over months or years.
Histology
- Graded on degree of cellular differentiation
- Less differentiated tumors show more aggressive growth pattern and have greater chance of metastasis
- Metastatic rate is less that 1-2% for small lesions
- Metastatic rate is up to 20% for tumors >4cm on the lips and ears
Pathogenesis
- Ultraviolet Radiation
- Chronic arsenic exposure = superficial
- Radiation treatment
- Human papilloma virus - 18, 16
- Immunosuppression -transplant patients -underlying cancer
- Chronic scars: burns, chronic ulcers, chronic osteomyelitis