Dysplastic nevi are often graded as showing mild, moderate or severe atypia. They may be associated with an increased risk of melanoma particularly in a familial setting but also one not uncommonly sees a dysplastic nevus adjacent to a melanoma suggesting progression. Although it is assumed by many that there is a progression through the varying degrees of atypia to [i]in situ[/i] and eventually invasive melanoma, this matter has not been fully resolved. With this as a background, the dermatologists in the US in particular are always keen to know the degree of atypia in any one dysplastic nevus.
While in Boston, it was my practice to recommend re-excision of dysplastic nevi as follows (in my practice, the dermatologists generally wanted treatment guidance):
· Mild cytological atypia- no re-excision unless the lesion was present at a margin
· Moderate cytological atypia- 2 mm margin re-excision
· Severe atypia- 5 mm margin re-excision (i.e. the same as for [i]in situ[/i] melanoma)
The basis for this advice was twofold:
· Firstly with any given biopsy (even if the margins appeared clear) there was always concern that unless one literally serial sectioned the specimen, one could not be absolutely certain that a margin might be involved somewhere in the specimen.
· Secondly, there was worry that there might be a more serious lesion left behind in the patient’s skin adjacent to the biopsy site. This was certainly borne out during the examination of the re-excision specimens on numerous occasions ranging from finding foci of more severe atypia through to in situ and even invasive melanoma.
The reason why this state of affairs has developed is that over the years the biopsy specimens have changed from excision of the whole lesion with clinically obviously clear margins to incomplete punch and even shave biopsies. I have always been against this practice arguing that if a lesion is clinically worrying then it should be excised [i]in toto[/i] such that complete examination of the lesion is possible and there will be no need for a re-excision. Sadly I was always a voice in the wilderness. This was largely because as a pathologist, I had no real interest in the cosmetic result. As far as I was concerned, if the lesion was fully excised at the initial surgery then I would know the exact diagnosis and if an invasive melanoma was present, I could make the appropriate treatment recommendation in my report.
The major practical problem with the very large number of incompletely excised dysplastic nevi received on a daily basis was that the subsequent re-excision specimens generated a huge increased workload such that I used to start looking at them at 4.00 or 5.00 am so that the residents would not have to waste hours gazing at the innumerable levels and I could keep back anything of interest to show them later.
I would be really interested to hear other viewpoints on this issue not only from the US but also to gain European, UK and other perspectives.