Recurrence of Melanocytic Naevi (Mole) is low after biopsy

Low rates of clinical recurrence after biopsy of benign to moderately dysplastic melanocytic nevi (DN).

Goodson AG, Florell SR, Boucher KM, Grossman D.

J Am Acad Dermatol. 2010 Apr;62(4):591-6. Epub 2009 Dec 16.

Clinical fear of melanoma leads to complete excision of dysplastic naevi (DN) when biopsy reveals postive margins. However this study opens the door to having a more expectative attitude.

• In this study the authors sought to establish the recurrence rates of previously biopsied DN, and to evaluate whether:

1. biopsy method
2. margin involvement (postive or negative margins)
3. congenital features
4. epidermal location
5. and degree of dysplasia are associated with the “mole coming back”.

• Patients having a history of a “nevus biopsy” at least 2 years earlier were assessed for clinical recurrence. Slides of original lesions were re-reviewed by a dermatopathologist.
• A total of 271 nevus biopsy sites were assessed in 115 patients. Of 195 DN with greater than 2 years of follow-up:

1. 7 (3.6%) demonstrated recurrence on clinical examination. In all, 98 DN had a follow-up period of at least 4 years with no clinical recurrence. No “severe” DN were included in the study.
2. Of 61 benign nevus biopsy sites examined, clinical recurrence was observed in two (3.3%).
3. For all nevi, recurrence was more likely if a shave biopsy was performed.
4. There were NO increased chances of recurrence associated with:
   1. nevus dysplasia or subtype (note that no severe DN were included in the study)
   2. positive margins
   3. congenital features

The excision of naevi might not be necessary as the authors wish to conclude. However the authors admit to the high interobserver variability: indeed 21% of lesions diagnosed as melanoma lesions were initially diagnosed as DN in a study (1). In the same study, the opposite was true when 12% of lesions were diagnosed as DN when they were initally diagnosed as melanoma in situ.

Also “moderate” or “severe” dysplasia of a melanocytic nevus is somewhat subjective as precise definition is lacking. And as some would consider severe dysplastic nevus as a melanoma in situ as shown just above personally, we would  excise moderate or more dysplastic melanocytic naevi, this attitude would be even more advocated in low skin phototypes or in patients with a personal or family history of melanoma. It is better to have a bigger scar than a melanoma, regardless of its depth, and regular follow-ups are in both situations mandatory.

However mild-to-moderate dysplastic navi and benign nevi could be left alone judging from the conclusions of this study. Worth noting is that the authors didn’t mention that lesions which recurred might have been seen by another dermatologist. It would be interesting to do propsective studies taking into account the risk factors for melanoma obtained from history nd inital clinical examination.

(1). Inter-observer variation in the histopathological diagnosis of clinically suspicious pigmented skin lesions; Brochez L, Verhaeghe E, Grosshans E, Haneke E, Piérard G, Ruiter D, Naeyaert JM.; J Pathol. 2002 Apr;196(4):459-66.