7.2 Optimal primary excision techniques
Surgical excision is the removal of a tumour with a surrounding cuff of normal uninvolved tissue. The defect is then allowed to heal by second intention, or closed primarily (i.e. at the time of surgery) using methods such as direct closure, flap repair or graft repair, or secondarily (i.e. at a later time) by similar methods when histopathologic confirmation of clearance is complete.
A scalpel is not the only tool that can be used for excisions. Smaller excisions can be achieved with biopsy tools such as curettes or punch biopsies. Larger, more complex excisions, may require removal of composite tissues such as cartilage, bone, and other structures such as nerves if they are affected. The aim of treatment is to minimise the skin cancer’s impact on a patient’s quality of life. Therefore treatment regimens should be tailored to allow this.
The majority of keratinocyte cancers (KCs) can be excised under local anaesthetic on an outpatient basis. Excision of small, clinically favourable lesions in straightforward sites should be within the skills of general practitioners who are capable and confident in the performance of minor surgical procedures. The most widely used technique is excision with an adequate margin and direct closure. The definition of adequate margin differs depending on tumour biology and anatomical site.
Other techniques for high- risk tumours include Mohs micrographic surgery and complete circumferential peripheral and deep-margin assessment using intraoperative frozen section assessment (see: Criteria for choosing Mohs micrographic surgery in preference to other surgical techniques).
Preparation and excision
The outline of the tumour should be outlined, then an appropriate margin of excision marked. The method of excision (and if necessary repair) is then is also marked. The area is then adequately infiltrated with local anaesthetic and then sufficient time allowed to elapse for dense anaesthesia to occur. Incision should be made around the marked area with a scalpel until full thickness release of the dermis has been achieved circumferentially. Removal of the specimen from one end to the other can then usually be achieved with a single (not multiple) grasp of the specimen taking an adequate and even layer of subcutaneous fat under the dermis.
Lateral and deep margins are important. Lateral margins need to be adequate to ensure complete excision. While lateral margins are easier to define, deep margins require experience. Deep margins are often clear on histopathology if a thin layer of subcutaneous fat is taken, as most tumours do not extend beyond the dermis. Nonetheless, adequate deep margins are very important, and the practitioner must tailor their excision to give an adequate deep margin. Fear of damaging underlying anatomy and inexperience may cause incomplete deep margins in otherwise easily resectable tumours. The orientation of excisions is important. Other factors being equal, tumours should be excised along relaxed skin tension lines, but in a line that avoids distortion. Therefore, tumours should be excised radial to apertures and unique structures. Judging optimal orientation requires training and experience. An example of incorrect decision-making is to excise lesions parallel to the eyelid or eyebrow instead of radial to such structures.
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Excision specimens should be handled with care to avoid damaging margins. Multiple grasps of the specimen with forceps during excision should be avoided, as this can destroy margin evaluation. All specimens should be marked with a suture (or in such a way that the practitioner and the pathologist understand completely) and that location described absolutely (discrete anatomical location e.g. ‘root of helix’) or relatively (e.g. superior, inferior, lateral, medial, anterior, posterior, proximal, distal) so the histopathologist can accurately map margins.
Note that describing suture position as 12 o’clock or similar may be unhelpful unless it is known where 12 o’clock is located. The pathologist will usually designate the suture at 12 o’clock. This is particularly important when trying to assess the location of an incomplete margin, or when another practitioner has to do a wider excision.
When multiple excisions are performed, as with multiple biopsies, it is essential that specimens are labelled and the site can be identified unambiguously at a later date. Photographs, diagrams, and detailed descriptions are all useful and should be employed as appropriate.
Before the patient leaves the procedure room, the pathology specimens should be checked to confirm that a specimen is in each container and that they are labelled correctly with the patient’s name and address and the surgical site.
If the excision has been correctly planned, the defect can be closed directly in most cases. Virtually all KCs below the neck and above the knees, irrespective of size, can be closed directly. Many others on the lower leg and on the face can be treated likewise.
Other primary closure methods are flaps and grafts. While the majority of excisions do not need flaps or grafts, these may be required in certain defined circumstances. Flaps and grafts are used for defects:
- where closure of the defect would distort surrounding structures
- where the defect is too large to close directly
- where the defect is too complex, requiring the reconstruction of composite tissues or different cosmetic units.
Some areas can be allowed to heal by second intention.
Flaps should only be performed when clinically appropriate and by those with adequate surgical training. This technique needs careful planning and execution, and should not be offered by inexperienced operators. Poorly executed flaps can be a cause of morbidity in patients who would have had minimal morbidity if adequate planning had been undertaken and correct surgery had been performed.
A defect should not be closed with a flap if there is doubt as to the adequacy of excision. It is best to directly close, graft or leave open for secondary closure until such confirmation of histologic clearance has been achieved.
- Surgical treatment – Introduction
- Considerations before selecting a surgical treatment modality
- Post-surgical care and interpretation of the pathology report
- Protocol to manage incompletely resected basal cell carcinoma
- Protocol to manage rapidly growing tumours
- Criteria for choosing Mohs micrographic surgery in preference to other surgical techniques
- Surgical management of advanced cutaneous squamous cell carcinoma
- Surgical treatment – Health system implications and discussion
- Chren MM, Sahay AP, Bertenthal DS, Sen S, Landefeld CS. Quality-of-life outcomes of treatments for cutaneous basal cell carcinoma and squamous cell carcinoma. J Invest Dermatol 2007 Jun;127(6):1351-7 Available from: http://www.ncbi.nlm.nih.gov/pubmed/17301830.