Conventional surgery

by Verónica Ruiz

CONVENTIONAL SURGERY

The conventional surgery is one the most practiced surgical processes in dermatology and it is done for the exeresis of benign and malignant skin injuries.

It consists of the removal of both the injury and a variable peripheral surrounding margin of supposedly normal tissue to ensure the complete removal of the tumor.

Removing these additional margins means that the size of the surgical defect and the resulting scar may be visibly larger than the initial tumor.

As in Mohs surgery, the resulting surgical defect can be repaired by direct suture, if there is sufficient skin laxity to allow direct closure without causing anatomic distortion or functional impairment, or by mobilizing the adjacent skin, using and designing what we call “flaps”, or distant skin (called grafts).

Although CC presents differences with respect to Mohs surgery, it represents a valid option (and sometimes it is the best alternative) in the case of the removal of tumors located in the trunk and extremities (also sometimes on the face) and in certain tumor types.

Next, I will describe some relevant aspects in relation to the margins for malignant tumors and what are the advantages and disadvantages of CC with respect to Mohs surgery.

 
Which margins are meant to be used for malignant tumors?

The length of the peripheral margins of healthy skin to be removed in cases of malignant tumors varies depending on the type, size and location of the tumor, but, as a general rule, it usually ranges from 4 mm to several cm.

The excised piece will be examined later and deferred (after surgery) by a specialist in pathological anatomy, who will determine if the tumor has been completely excised with free margins (clean of tumor) or if, on the contrary, the margins are affected and there is tumor persistence.

Although there is no consensus regarding the definition of what we should understand as “negative surgical margins”, most specialists consider that there are free margins if they are observed between 4-6 mm without evidence of malignant cells from the edge of the tumor.

There is also no clear definition in relation to the consideration of close/proximal margins, but most specialists consider that a skin length without evidence of malignant cells ≤ 3 mm from the edge of the tumor would be considered as such.

The fact of having close/proximal margins may not have a significant effect on survival or the probability of tumor recurrence, but if in addition to other additional characteristics, such as the presence of lymphovascular or perineural invasion, the existence of proximal margins has been associated with higher rates of recurrence and worse survival rates.

 
What are the fundamental differences of conventional surgery versus Mohs surgery?
  1. Margins of healthy skin: While Mohs surgery preserves as much healthy tissue as possible adjacent to the tumor, being very useful in those areas where it is essential to maintain good cosmetic and functional result such as the face, CC is performed taking a “fixed” and standardized length of margins of visibly healthy skin around the tumor.
  2. Processing of the removed tumor: In Mohs surgery, the entire excised sample is examined in situ, while in CC only a small percentage of the specimen is analyzed (generally at the level of the margins of the specimen) and delayed.
  3. Duration of intervention: The fact that Mohs surgery allows, in most cases, the processing and analysis of the tissue simples excised at the same time of the intervention, makes the duration of this technique longer than the CC, since in the latter, the excised piece is sent for analysis by the pathological anatomy after the surgery.

Sometimes, within the CC, “perioperative or intraoperative biopsies” of the surgical margins are performed, which consist of performing the histological study during the surgical intervention, and has the objective of guiding the surgeon on the existence or not of tumor persistence.  However, in this modality, neither the entire piece nor the margins are analyzed, but only a small part of the sample.

 

REFERENCES

  • Michael M Li, Sidharth V Puram, Dustin A Silverman, Matthew O Old, James W Rocco, Stephen Y Kang. Margin Analysis in Head and Neck Cancer: State of the Art and Future Directions. Ann Surg Oncol 2019 Nov;26(12):4070-4080.
  • Mara C Weinstein, Robert T Brodell, Jeremy Bordeaux, Kord Honda. The art and science of surgical margins for the dermatopathologist. Am J Dermatopathol 2012 Oct;34(7):737-45.
  • Donita Dyalram, Steve Caldroney, Jonathon Heath. Margin Analysis: Cutaneous Malignancy of the Head and Neck. Oral Maxillofac Surg Clin North Am 2017 Aug;29(3):341-353.