The return of pigment after a shave biopsy usually does not mean that you had a melanoma originally. A shave biopsy, if the entire mole was not taken out, will often lead to what is termed a recurrent nevus. What happens, is that the deeper mole cells ( melanocytes) are now exposed to the sun and gain the ability to pigment. That is why it is important to wear a sunscreen after a shave biopsy.
There are two signs that weigh for a recurrent nevus rather than a melanoma.One is if the pigmentation formed within a few months of the shave biopsy. The second sign is if the pigmentation is within the scar site.
It is important for you to return to the dermatologist who performed the shave biopsy so that he/she either perform a re-excision with a punch or excision technique or at least ask the pathologist to review the slides. I personally, re-biopsy to be conservative and extra cautious.
It is important for the dermatopathologist to be aware of the fact that the mole was previously biopsied. The scar formed from the shave biopsy can distort the melanocytes, making them appear more ominous than they really are.
The shave technique should really be used only in two circumstances. One, if the physician ( and patient) are entirely confident that the mole is benign and that the shave technique will afford the patient a better cosmetic result. The second instance would be under circumstances where the physician is concerned about a lentigo maligna, especially on the face. These can be quite large and a standard biopsy might prove quite disfiguring. Some physicians prefer biopsying only the suspicious areas, while others feel a wide shave excision will encompass the whole lesion. Since a lentigo maligna ( Hutchinson's freckle) is, by definition superficial this would be a reasonable option. Lentigo Maligna is a skin lesion, usually seen on the face of elderly people. If there is invasion into the dermis, the Lentigo Maligna has balefully morphed into a lentigo maligna melanoma. Unlike other melanomas, the Lentigo Maligna Melanoma is associated with chronic sun exposure, like basal cell carcinomas and squamous cell carcinomas.
There are three reasons we dermatologists do not like shave biopsies for suspicious lesions. First, a shave biopsy may leave melanoma cells that are deeper than the shave biopsy cut. This is unusual, but can happen.
Second, it becomes nearly impossible to judge the level of the melanoma. This can be very important both in prognosis and treatment. For instance, whether to perform lymph node biospies or exploration. We would not think of a time consuming and expensive exploration if the level was say Breslow 0.11. However, a Breslow level 3.2 would necessitate a thorough exploration.
Finally, when I am quite suspicious, and the lesion does turn out to be a melanoma. I would rather tell the patient the bad news ( you have a melanoma) with some good news, (we have removed the whole thing). Patients are still referred to a surgical oncologist, plastic surgeon, or general surgeon specializing in melanoma treatment, depending on location. But at least, there is far less anxiety while the patient is waiting for their appointment and more definitive surgery.