Non-melanoma skin lesions

Basal cell carcinoma
Basal cell carcinoma (BCC) is also commonly referred to as a rodent ulcer or basalioma. BCC is the most common type of cancer in Europe, Australia and the US Caucasian population but it is rare in Africans, Afro-Caribbean and Asians; and extremely rare in oriental races. BCCs arise due to solar damage and ionising radiation; they also occur in burn scars and vaccination sites (Burns et al., 2004). There is a worldwide increase in the incidence of BCCs, and the significant aetiological factors include a genetic predisposition and exposure to UV radiation (sun exposure in childhood is indicated). Other risk factors include: increasing age, males, fair skin types I and II, immunosuppression and arsenic exposure (Telfer et al., 2008). The tendency to develop multiple BCCs is a feature of Gorlin syndrome (basal cell naevus syndrome).

BCC is defined as a malignant tumour, which rarely metastases and is composed of cells similar to those in the basal area of the epidermis and its appendages (Burns et al., 2004) (see Figure 11.3). BCC is a slow growing but locally invasive tumour which infiltrates tissues through a three- dimensional growth pattern. BCCs will continue to develop and grow and may cause extended local tissue invasion and destruction, particularly, on the face, head and neck (Telfer et al., 2008).


Types of BCC
There are several types of BCC and classically they arise in skin of a normal appearance. They can also vary in size from a few millimetres to several centimetres in diameter. There are several different clinical presentations of BCC, which are outlined in Table 11.2 (DermNet NZ, 2009a).

Table 11.2 Different clinical presentations of BCC.   Nodular BCC Most common type on the face Small, shiny, skin-coloured or pinkish lump Blood vessels cross its surface May have a central ulcer so its edges appear rolled Often bleeds spontaneously then seem to heal over Cystic BCC is soft, with jelly-like contents Rodent ulcer is an open sore Micronodular and microcystic types may infiltrate deeply   Superficial BCC Often multiple Upper trunk and shoulders, or anywhere Pink or red scaly irregular plaques Slowly grow over months or years Bleed or ulcerate easily   Morphoeic BCC Also known as sclerosing BCC Usually found in mid-facial sites Skin-coloured, waxy, scar-like Prone to recur after treatment May infiltrate cutaneous nerves (perineural spread)   Pigmented BCC Brown, blue or greyish lesion Nodular or superficial histology May resemble melanoma   Basisquamous BCC Mixed BCC and SCC Potentially more aggressive than other forms of BCC     Source: Reproduced from DermNetNZ (2009a).

Diagnosis and definition of high- and low-risk BCCs
BCCs are diagnosed by examining the suspect lesion in good light and with the optional aid of a dermatoscope. If clinical doubt exists, a punch biopsy may be performed. Imaging techniques may also be used where bony involvement is suspected (Telfer et al., 2008). BCCs are treated with either surgery or other noninvasive techniques. The chosen treatment almost always results in a cure; although BCCs can reoccur at the same sites. Metastatic BCC is extremely rare and can be fatal; this involves a BCC that has spread to the lymph glands and other organs.

The British Association of Dermatologists (BAD) guidelines for the management of BCC (Telfer et al., 2008) recommend that high-risk BCCs, defined as those most likely to reoccur, are excised with predetermined margins or Mohs micrographic surgery is performed. High-risk BCCs also includes previous treatment failure and patients who are immunosuppressed. The features of high-risk BCCs are defined by the factors in Table 11.3.

Table 11.3 Factors affecting the prognosis of BCC. Tumour size Tumour site Tumour type and definition of tumour margins Growth pattern/histological subtype Failure of previous treatment (recurrent tumours) Immunocompromised patients     Source: Reprinted from Telfer et al. (2008).

Treatment of BCC
Low-risk BCCs, tumours that do not confer with the features in Table 11.3, are generally treated with a variety of destructive surgery and non-surgical techniques.

Curettage and cautery and cryotherapy procedures may be used. Cryotherapy, although convenient and less expensive than surgery or radiotherapy, has poor cure rates in comparison with surgery and radiotherapy, especially for lesions greater than 2 cm; surgery also provides a better cosmetic effect (Bath-Hextall and Perkins, 2008). Carbon dioxide laser is an uncommon treatment with poor evidence to support its use. Non-surgical techniques include topical immunotherapy, PDT and radiotherapy.

Topical immunotherapy
There is a good evidence for using topical immunotherapy to treat primary and superficial BCC (Telfer et al., 2008). Imiquimod is the only topical immunotherapy licensed for the BCCs but is not indicated for BCCs on the face (Electronic Medicines Compendium [EMC], 2009). Imiquimod cream is applied over the treatment area, including 1 cm of skin surrounding the BCC. Before applying Imiquimod cream, patients should wash the treatment area with mild soap and water and dry thoroughly. Sufficient cream should be applied once a day (at bedtime is ideal) and rubbed into the treatment area until the cream vanishes. Imiquimod cream remains on the skin for approximately 8 hours; showering and bathing should be avoided. After this period it is essential that Imiquimod cream is removed with mild soap and water, and the hands are washed thoroughly (EMC, 2009).

Imiquimod cream can be applied for 12 weeks and treatment response can then be assessed. If the treated tumour shows an incomplete response, a different therapy should be used. A rest period of several days may be taken if the local skin reaction to Imiquimod cream causes excessive discomfort to the patient, or if infection is observed at the treatment site. In the latter case, other appropriate measures should be taken (EMC, 2009).

During therapy and until healed, affected skin is likely to appear noticeably different from normal skin. Local skin reactions, such as pruritus, burning, irritation and pain on application site, are common but these reactions generally decrease in intensity during therapy or resolve after cessation of Imiquimod cream therapy (EMC, 2009).

Photodynamic therapy
Photodynamic therapy (PDT) is a procedure which causes a photochemical reaction within tumour cells due to the reaction with a photosensitising agent (methyl aminolevulinate cream), red light and cellular oxygen. This procedure destroys the targeted tumour cells by apoptosis and necrosis (Buchanan and Courtenay, 2006). PDT is indicated for superficial BCCs, Bowen’s disease and AK. A PDT light source is used by a trained clinician within a dermatology clinic. The lesion is prepared by gentle decaling; a photosensitising agent is applied and several hours later (usually between 3 and 6 hours to allow the drug to concentrate in the cancer cells), the lesion is then illuminated with red light. Following treatment, the lesion site will form a scab, which will fall off after 3 weeks. More than one lesion can be treated in a session, and PDT can be repeated after a 4-week interval (National Institute for Health and Clinical Excellence [NICE], 2006b).

Radiotherapy
Radiotherapy is a less commonly used therapy to treat BCCs. It is effective for primary and recurrent BCC and is generally suitable for high-risk older patients who are unable to tolerate surgery. Good cosmetic results are achieved using superficial radiotherapy (generated at up to 170 kV) as once-weekly treatments for several weeks (Telfer et al., 2008).

Prevention of BCC
Advice on sun protection and sunscreens is crucial, as people with BCCs have a high risk of developing further BCCs; also they have an increased risk of developing other skin cancers. Patients should be advised to complete skin selfexamination (SSE) and seek the opinion of a clinician if they have any suspected moles or other skin lesions.