Basal cell carcinoma - Skin tumours

Skin tumours

Basal cell carcinoma

Definition

Basal cell carcinoma (BCC) is a locally invasive skin cancer arising from the basal layer of epidermis.

Incidence

Approximately 75% of all skin tumours.

Age

Increases in incidence with age.

Sex

M > F

Geography

Most common in Caucasians, and uncommon in dark-skinned populations.

Aetiology

Basal cell carcinomas are predisposed to by light and ionising radiation. Sun exposure is the most important aetiological factor particularly in individuals with fair skin, pale eyes and red hair. Childhood sun exposure appears to be important, especially if there is repeated intermittent intense exposure.

Pathophysiology

Mutations in the tumour suppressor gene and patched (PTCH) on chromosome 9 have been identified in both sporadic basal cell carcinoma and familial basal cell nevus syndrome. As with other tumour suppressor genes both copies need to be damaged before tumours develop. With the familial form, patients inherit one inactive gene and are therefore susceptible to tumour development. Only a minority of basal cell carcinomas become locally aggressive or metastasise.

Clinical features

Most basal cell carcinomas occur on the face. And three patterns are recognised:

·        Nodular basal cell carcinoma is the most common type (60%) appearing as a firm pink-coloured raised nodule, often with telangiectatic vessels within the nodule. Central ulceration is common (rodent ulcer).

·        Superficial basal cell carcinoma (30%) occurs on the trunk as a flat scaly red plaque, often with an irregular micropapular edge.

·        Morphoeic basal cell carcinoma (10%) is typically flat smooth, flesh-coloured, or a plaque with indistinct edges.

Investigations

Suspicious lesions are investigated by excision biopsy.

Management

Complete excision is curative, local recurrence may occur especially with morphoeic and superficial types. Radiotherapy can be used for large superficial carcinomas especially in older patients.

Prognosis

Excision achieves a 95% cure with a recurrence rate of 5% at 5 years.