Size of Mohs Wound. Could The Doctor Have Left A Smaller Scar?

In general use of Mohs results in smaller wounds than produced by non-Mohs techniques.  Certain cancers require large resections.  See examples in the link below

Mohs surgery is a technque that maximized the cure rate and minimized the scar size. This is achieved by how the skin cancr is removed from the skin and sampled to check the margins. It is common that tumors are removed completely in the first "layer" or stage. It is likely that the size of your girlfriends defect and resultant scar was minimized by using the mohs technique.

 

Mohs surgery is really the best way to control tumor margins and obtain the smallest defect after skin cancer removal. On average these defects would be smaller than non mohs surgical approaches.

The first and most important priority of Mohs surgery is to cure the cancer.  The second priority is to conserve tissue, but cure of cancer remains the top priority.  Typically the Mohs surgeon will remove a small amount of normal skin around the visible area of tumor and/or scar.  There is always going to be some variability in how much "normal" skin is removed along with the skin cancer.  This varies depending on the surgeon, the type of tumor (more aggressive tumors such as squamous cell cancer might justify more skin removal), the age of the patient, the exact location on the face (for example, the eyelid is a location where skin sparing is critical), whether or not the tumor is recurrent, etc.    

MOHs is really the best way to remove skin cancer while preserving tissue,     Having said that, it is important to realize that the tumor may have been larger to begin with than one might have thought.  Remember, the object of MOHs surgery is to completely remove the cancer and in order to properly ascertain if the tumor is completely removed, it is also necessary to take a margin of normal skin.  This, in addition to a larger than expected tumor can result in a bigger than expected wound. 

Usually the size of the first level is determined by the initial biopsy done. I have literally done tens of thousands of Mohs procedures over my career. When I do a biopsy and the read comes back from the lab, I can often tell how much wider and deeper I need to go with the first cut. And often I can get the full piece with one cut, and not need to go larger and wider and deeper with more and more levels. There's not a rule of thumb so to speak, but it depends on the site, the initial biopsy report, and the experience of the doctor performing the procedure. The purpose of Mohs is to preserve as much skin as possible and remove the tiniest amount possible for the smallest scar.