Squamous cell carcinoma (SCC)

Squamous cell carcinoma is defined as a malignant tumour arising from the keratinocytes of the epidermis (see Figure 11.4). SCC has the potential to metastasise; spread is almost always by the lymphatic route (Burns et al., 2004). Unlike BCCs, SCCs do not often arise in healthy skin and usually present as an indurated nodular keratinising or crusted tumour, or as an ulcer without the evidence of keratinisation. SCC is the second most common skin cancer, and the incidence has been rising since the 1960s (Preston, 1992). Aetiology is usually related to chronic UV light exposure, especially in fair-skinned individuals, those with albinism or xeroderma pigmentosum. SCC may also develop as a result of previous exposure to ionising radiation, arsenic; or within chronic wounds, scars, burns or from pre-existing lesions, such as Bowen’s disease (Motley et al., 2002).

Diagnosis of SCC
The diagnosis of SCC is generally established by histology. Punch biopsies will be performed to provide a tissue sample, which will be assessed by histology and a report produced outlining the pathological pattern (e.g. adenoid type), cell morphology (e.g. spindle cell SCC), degree of differentiation (e.g. poorly or well differentiated) and the histological grade. SCC grading is by Borders’ classification system; grades 1, 2 and 3 denote ratios of differentiated to undifferentiated cells (Motley et al., 2002).

Treatment of SCC
The treatment of choice for all resectable SCCs is surgical excision; Mohs surgery is recommended for high risk and recurrent SCCs. Small and well-defined, low-risk SCCs are generally treated by curettage and cautery or cryotherapy. Radiotherapy may be indicated for non-resectable tumours (Motley et al., 2002).

Prevention of SCC
Patients with SCCs require follow-up for recurrent skin cancer. Patients should be instructed in self-examination. Early detection and treatment improves patient survival from recurrent disease. Ninety-five percent of local recurrences and 95% of metastases are detected within 5 years (Motley et al., 2002).