|A 60-year-old woman presented with a nine-month history of a crusty skin lesion that kept scabbing. It was not itchy or painful. It had become significantly larger over the past three months, but otherwise had not changed in appearance. There was no history of immunosuppression.
On clinical examination, there was a 3cm diameter crusty nodule with some induration at the base. The nodule was not tender on palpation. The appearance was suggestive of primary cutaneous squamous cell carcinoma (SCC). The patient was referred under the two-week wait pathway.
SCC may arise from keratinocytes and can be locally invasive or may metastasise. It is the second most common skin cancer after basal cell carcinoma1 and the incidence of both is increasing.
SCC occurs more commonly in patients with albinism and xeroderma pigmentosum.1 It also occurs in photoaged skin resulting from UV light exposure, in which case it is more likely to arise on the head and neck and other sun-exposed sites.1
It may be related to immunosuppression, burn scars, ulcers, Bowen’s disease or exposure to ionising radiation.1,2 The main precursor of cutaneous SCC is actinic keratosis. HPV infection has also been linked to the development of cutaneous SCC.2
Immunosuppressed patients who have undergone organ transplantation are at increased risk of SCC, so skin surveillance is important.1 Risk is also increased in those with fair skin and a history of sun exposure, particularly sunburn in childhood.1
SCC may present as a keratinising or crusty nodule, which may be indurated at the base or may ulcerate.2 If there is a suspicion of SCC, the patient should be referred urgently to see a dermatology specialist.2 The diagnosis may be confirmed histologically, usually by excisional biopsy.
The pathology report will indicate the histopathological subtype and grade (Broder’s classification), Clark’s level, degree of differentiation and tumour depth.2 In addition, perineural, vascular and lymphatic invasion may be present.3 The report should also indicate the excision margins.
These factors are relevant to the prognosis, as are anatomical site, rate of growth and immunosuppression. For example, there is an increased risk of metastasis with sun-exposed sites and lesions >2cm in diameter.2 Tumours more than 4mm in depth are more likely to recur and have greater metastatic potential.3
Management is aimed at complete excision of primary cutaneous SCC, histologically confirmed by adequate surgical margins. However, RCTs of treatment modalities are lacking. SCC may be locally invasive and local ‘in transit’ metastases may be discontinuous with the primary lesion.2 Wider surgical excision, as well as radiation therapy, may be considered.
Surgical management encompassing surgical excision and Mohs micrographic surgery has the advantage of providing a specimen suitable for histological analysis and allowing for assessment of surgical margins. A margin of 4mm would be appropriate for a well-defined, low-risk tumour that is <2cm in diameter, because this would be curative in 95% of cases.2
Surgical management represents the best strategy for treatment of primary cutaneous SCC. Mohs micrographic surgery may be the more appropriate option for high-risk tumours and in areas where wide surgical margins would be difficult to achieve, such as the face.4
Curettage and cautery may be appropriate for small, well-differentiated, slow-growing primary cutaneous SCC in selected patients.2 However, histological assessment is more difficult on a sample obtained by curettage and assessment of surgical margins cannot be made.
Cryosurgery may be used for small tumours that have been histologically confirmed as SCC. In some circumstances, radiotherapy may produce a more acceptable cosmetic result than excisional surgery.4
Other treatment modalities reported in the literature include topical imiquimod and photodynamic therapy.2
Patients with a history of high-risk primary cutaneous SCC should be followed up for at least two years and for up to five years.2,5 Most patients with primary cutaneous SCC have an excellent prognosis.1 The risk may be reduced by avoiding sun exposure, and using sunscreens and protective clothing.1
- Dr Suneeta Kochhar is a GP principal in Bexhill, East Sussex
Competing interests: None declared
1. Garcia-Zuazaga J, Olbricht SM. Adv Dermatol 2008; 24: 33-57.
2. Motley RJ, Preston PW, Lawrence CM. Multi-professional Guidelines for the Management of the Patient with Primary Cutaneous Squamous Cell Carcinoma. London, British Association of Dermatology, 2009.
3. Cassarino DS, Derienzo DP, Barr RJ. J Cutan Pathol 2006; 33: 191-206.
4. Alam M, Ratner D. N Engl J Med 2001; 344: 975-83.
5. Rowe DE, Carroll RJ, Day CL Jr. J Am Acad Dermatol 1992; 26: 976-90.