A 79 year old man with a lesion on his cheek

Short answer

Basal cell carcinoma.

Long answer

Basal cell carcinomas are slow growing malignant tumours that arise from the stratum germinativum, the deepest layer of the epidermis.1

Dermatoscopy (examination of skin lesions with a handheld dermatoscope) typically shows a cystic pearly appearance with raised areas of telangiectasia. However, several histological subtypes exist, and their morphology and distribution on the body differ, as summarised in the table⇓).

Short answer

Malignant.

Long answer

Basal cell carcinoma is a malignant tumour that invades the epithelial basement membrane. Although slow growing, it may cause extensive tissue damage and morbidity by invading surrounding tissues. The older term “rodent ulcer” comes from the Latin “rodens”—to gnaw. Basal cell carcinomas almost always remain localised to the site of presentation. Metastasis is rare (0.0028%),5 and when reported it is usually related to neglected or recurrent lesions.6

Short answer

The main risk factor for basal cell carcinoma is exposure to ultraviolet light.2 Genetic risk factors include having fair skin, blue eyes, or red hair and having a family history of skin cancer. Acquired risk factors include exposure to ultraviolet light, radiation injury, immunosuppressive drugs, and trauma.

Long answer

Exposure to ultraviolet light (natural and artificial) is the main risk factor for developing basal cell carcinoma (box 1).2 Ultraviolet light leads to the formation of thymine dimers in the DNA of basal cells. Despite cellular mechanisms to repair this damage, some thymine dimers may not be repaired, resulting in permanent DNA damage. Cumulative DNA damage can lead to DNA mutations.

About 2% of skin cancers develop in people with a strong genetic predisposition. In patients with multiple tumours, conditions such as Gorlin’s syndrome (naevoid basal cell syndrome, in which a tumour suppressor gene at chromosome 9q22.3 is mutated) should be considered.

Short answer

This is a high risk lesion because it is on the central face, one of the areas identified by the National Cancer Peer Review Programme as having a high risk of recurrence after treatment.8

Long answer

This lesion has a high risk of recurrence because it is on the central face around the eyes. Basal cell carcinomas are classified into high or low risk depending on their likelihood of recurrence after treatment. Box 2 summarises the features associated with a high risk of recurrence. For the purpose of referral, low risk basal cell carcinoma is considered to be any other basal cell carcinoma.

Surgery remains the treatment of choice for high risk lesions. Non-surgical treatments may be considered for low risk lesions.2

Short answer

This basal cell carcinoma should be treated by surgery (wide local excision or Mohs micrographic surgery).

Long answer

This basal cell carcinoma should be treated by surgery (wide local excision or Mohs micrographic surgery).

The choice of treatment depends on the anatomical location, size of the tumour, histological diagnosis (if available), and fully informed patient preference.2

Wide local excision of this basal cell carcinoma requires a 4-5 mm clinical margin of healthy tissue around the lesion horizontally and that all of the dermis (down to the next layer) is included.5 Specimens are sent for histological analysis.

In Mohs micrographic surgery, resection occurs in stages, with comprehensive histological analysis of the margins between each resection in a process that takes hours or days. The technique may be indicated in high risk tumours around the face, those with poor clinical definition of margins, recurrent lesions, or those with perineural or perivascular involvement. Mohs micrographic is more expensive than wide local excision, and the comparative cure rates of the two treatments are unclear.5