First, let us dispose of the idea of a trip to the oncologist. Oncologists don't remove moles: some may NEVER have removed a mole in their career; others maybe 1-2 during a dermatology rotation. Your husband's trip to the oncologist might be the source of brief levity in an otherwise depressing day, but nothing more.
The classifying of atypical nevi from mild to moderate to severe is a histopathologic grading system. As Dr. Allen mentions, atypical nevi are best regarded as a continuum ranging between totally benign nevi and melanoma. Most dermatopathologists and dermatologists have adapted the term atypical nevi, as dysplastic nevi and before it the B-K Mole syndrome were felt to cause confusion. ( B-K was named after the original patient when Drs. Wally Clark and the affable and brilliant Marty Mihm first described these odd moles with a tendency to turn bad).
The pathologist looks at the architecture of the mole and the nevus (mole) cells themselves. This information is often buried in the description of the report, but is actually quite crucial. Architectural disorder is not nearly as serious as dysplasia. The atypical mole will generally be graded on the degree of dysplasia. The pathologist carefully looks at the cells: are they larger than the should be? Is the nucleus bigger or darker than normal. In looking at slides with Dr. Mihm, he always stressed the color of the nucleoli. Others, like the late Bernie Ackerman, tended to look at the way cells were grouped, what they were trying to do, their cohesion or lack of cohesion.
Taking all this information into consideration the pathologist will determine the degree of atypia ( dysplasia) and convey his or her impression to the dermatologist. I would say all dermatologists believe in a total excision of lesions described as having severe atypia and the vast majority would extend that action to those designated as moderate atypia.
It is in the realm of the mild that there may be some disagreement. Many pathologists will call a mole with only architectural disorder mild atypia. Some will note a few cells that look a bit strange as mild dysplasia or atypia. Some dermatologists will then opt for a total excision, while others will not. Some, like myself, on many occasions, will call the pathologist who interpreted the slide for some guidance.
One advance that should relieve you ( I know it does me and doubly true for the pathologists of the world) is the cocktail of stains available now for the pathologist. These immunoperoxidase stains will help the pathologist determine whether the mole is benign or malignant. This takes away some of the human judgement. Thus, if a nevus is graded as mild dysplasia, and the stains confirm a benign diagnosis, one is more comfortable in leaving a mildly atypical nevus alone.
These stains, should also re-assure you and your husband, that he does not have melanoma.
Of course, another factor, is that the report will tell you whether the whole lesion has been removed...that the margins are clear. Perhaps, in your husband's case, they were on the mild dysplasia and certainly nothing more need be done. It should be noted that sometimes, the pathologist will advise ( or even urge) us to re-exise, even with clear margins if there was very severe dysplasia ( and say inflammation and a few nevus cells transversing up the epidermis where they shouldn't be).
So, in your husband's case, maybe the dermatologist had already obtained clear margins on the mildly atypical nevi and felt no need to subject your husband to another excision. Maybe, there was only architectural disorder, another reason to keep the scalpel in the drawer.
One thing we would all agree on is that you should examine your husband's skin for moles once a month. With a documented severely dysplastic nevus, he should also be examined by your dermatologist every six months. You both should listen as the dermatologists goes over the A ( asymmetry) B (Border irregularity C ( color variegation ) D (greater than 6 mm) and E ( Evolving or changing) warning signs. I would also consider Mole Mapping in which digital photographs are kept in a computerized camera of all the moles, looking for changes in subsequent visits.
Vigilance is the key.