General considerations

Such procedures are often carried out in general practice. Standards have been set and guidelines produced on how personnel, premises, procedures and equipment should be organised. These are outlined in the separate article Minor Surgery in Primary Care.

It can be appreciated from these articles that there are a number of important issues to be considered before undertaking these techniques. These include:

• Consent (see also separate article Medical Ethics)
• Local anaesthesia techniques
• Infection control
• Staff training
• Audit
• Premises
• Handling and collection of specimens

Techniques

Incisional biopsy

• If the lesion is large and malignancy is not suspected it is acceptable to perform an incomplete excision. This is often called an incision or incisional biopsy. It is usually recommended that the specimen include an area of normal skin.
• An excision biopsy should aim to remove the whole lesion, especially if malignancy is suspected, with an edge or margin of normal skin included around the lesion. The size of this margin is the subject of some debate in the case of melanoma and suspected melanoma.
• Most lesions are round (or nearly so) but an ellipse of skin has to be removed to obtain satisfactory closure. The long axis of the ellipse should be in the direction to produce the best scar. Langer's lines are a useful guide but wrinkle and contour lines are also important and generally now preferred.^[1] This can be appreciated by examining parts of the body. Remember that lesions have 3 dimensions and it is important to biopsy deeply enough, usually including some subcutaneous fat. Sometimes this requires resorbable sutures to be buried in the fat layer to get good apposition. A few neat silk or vicryl sutures are usually the best way to close the skin.
• Be sure to get an adequate specimen and handle it with care as crushing it will make histological interpretation more difficult.

Punch biopsy

• This is not used very often in general practice. Patients will usually have been referred to a dermatologist and punch biopsy is used when a full thickness biopsy is required. It will usually be used for benign rashes and skin disorders to assist diagnosis.
• The instruments for punch biopsy come in various sizes and are usually 2 to 8 mm in diameter. Choose an appropriate size.
• Having achieved local anaesthesia, stretch the skin at 90? to the tension lines. Rotate the skin punch into the dermis, being sure to get an adequately deep specimen. Remove the punch when it enters the subcutaneous fat and beware of underlying structures such as nerves or vessels. Raise the specimen above the incision. A 21 gauge needle is advised rather than forceps that may crush the specimen. Cut the specimen free with tiny iris scissors.
• Normally a 2 mm or 3 mm punch does not require a suture to the skin but a larger one will need 1 or 2 sutures to close the wound and possibly to aid haemostasis.

Shave biopsy

• This is used with protruding skin lesions such as skin tags, actinic keratoses^[2] and seborrhoeic keratoses. It can be used for basal cell carcinomas.
• It usually requires local anaesthetic.
• It can usefully be combined with cautery to arrest bleeding and promote healing.
• After cautery, a plaster can be applied.

Specimens

• Specimens should be handled with care and if more than one is taken it is imperative to label which is which. If the report says that it is an incompletely excised malignancy, it is necessary to know which site this referred to. Specimens should be placed in a container and covered liberally with 10% formalin to give free immersion. The exception to this is specimens for microbiology that require the appropriate transport medium and specimens for immunofluoresence that require a specific medium. If there is any uncertainty then discuss it with your local laboratory.
• There is no hurry to get specimens in formalin to the laboratory but specimens for microbiology should arrive as soon as possible and specimens for immunofluoresence should be examined within 36 hours.
• Make sure that the container is properly labelled and, on the request form, give as much information as possible. See this as a doctor-to-doctor referral to an histopathologist. The more the histopathologist knows about the patient and the specimen the more helpful he or she can be. If available, a rubber stamp to illustrate the site of the lesion can be helpful.^[3] A picture paints a thousand words.
• Some authorities advise that anything removed at minor surgery should be sent for histology. If there is any doubt about the diagnosis this is wise but, when the doctor has no doubt about the clinical diagnosis, it does seem extreme. Sending skin tags for histology is a waste of time, money and valuable resources. A Dutch survey found that there was often discrepancy between clinical and histological diagnosis.^[4] The figures were 31% for GPs, 32% for surgeons and 17% for dermatologists. It would seem that an appropriate policy is the very liberal but not invariable use of histology.

Management of suspicious malignancy

Most skin lesions removed in general practice will be benign.^[5] The confidence and competence of GPs is influenced by training and experience. In countries with a high prevalence of skin cancer GPs will gain more experience of diagnosing and treating skin cancer. Where malignancy is suspected, referral is usually appropriate. When undertaken it is generally the best policy to attempt to remove all of the lesion. Lesions must not be treated by destructive techniques such as electrocautery because this technique does not allow histological diagnosis and confirmation of complete excision.

• Basal cell carcinoma (BCC) is suitable for biopsy, even punch biopsy, although excision biopsy with a margin may be better. Complete conventional excision is associated with a very low rate of recurrence over the subsequent 5 years.^[6] What the margin should be is a matter of some debate.^[7][8] In an analysis of peripheral and deep margins of histological clearance, around 1539 consecutive BCCs excised by conventional surgery showed that 81 lesions (5.3%) were incompletely excised peripherally; 36 lesions (2.3%) were incompletely excised deeply; 13 lesions (0.8%) were incompletely excised peripherally and deeply.^[9] Incomplete excision requires appropriate follow-up with further excision, radiotherapy or even observation and the outcome can be excellent.^[10] It should be remembered that in completely removed BCCs, apparent recurrences may well be new primaries.^[11] Lesions on the head and neck have a higher rate of incomplete excision and other risk factors have been identified.^[12] Lesions with a high risk of recurrence or incomplete excision should be referred.
• Squamous cell carcinoma of skin is also suitable for punch or excision biopsy. Again, excision margins are a subject of debate. A 5 mm margin has been suggested.^[13] Incomplete excision in the head and neck areas is common and these should generally be referred for excision.^[14][15]
• Malignant melanoma is suitable for an attempted wide excision but punch biopsy should not be used, as it makes it impossible to stage the lesion. It is not uncommon to find that excision is incomplete. This does not matter if it is followed by referral to a plastic surgeon who will perform the necessary surgery. A survey from London found that GPs often failed to excise the whole lesion and that a confident diagnosis was made in only 17% before operation.^[16] Amelanotic lesions were a particular problem. A survey from Edinburgh concluded that GPs need to think more often of malignant melanoma when they excise pigmented lesions and, when they consider this tumour a possibility, should perform an excision biopsy with a lateral clearance of at least 2 mm.^[17] However, much wider margins of 2 cm are likely ultimately to be required.^{[18][19][20][21][22]} Better results are claimed by dermatologists in one study comparing dermatologists, surgeons and GPs.^[23]

Audit

Minor surgery as a whole is a very suitable area for audit and is actively encouraged in the new guidelines.

• How many procedures were performed in the year and in which category?
• Who performed them?
• How many were not done in the practice but sent elsewhere?
• In how many was there a tissue diagnosis?
• Did it confirm the clinical diagnosis?
• How many were malignant?
• Review all complications. Is there a pattern that suggests that clinical protocols should change?
• Is there a pattern that suggests that an operator should refrain from minor surgery or undergo further training?