What Could Be the Cause of This Mole?

A 31-year-old female presented for evaluation of an asymptomatic mole on her external vulva of unknown duration. It was first noticed while personal grooming in the bikini area. 

What could be the cause of the mole?

A.    Benign nevus 
B.    Dysplastic nevus
C.    Melanoma
D.    Nevus of special site
E.    Folliculitis 

Answer on the next page.


Answer: Benign nevus

This melanocytic lesion exhibited features consistent with a melanocytic nevus of special site. Within the spectrum of nevi, there exists a group that presents in certain anatomic locations with histologically worrisome features but nonetheless benign behavior. This group of nevi has been broadly categorized as nevi of special sites.1 The anatomic locations affected by this group include the embryonic milk line (breast, axillae, umbilicus, and genitalia), flexural areas, acral surfaces, ear, and scalp. No further treatment was warranted. 

Because these lesions appear ominous on histology, it is imperative that the precise anatomic location be identified on the pathology request sheet and that an experienced dermatopathologist render the diagnosis to avoid inappropriate overtreatment.

1. Mason AR, Mohr MR, Koch LH, Hood AF. Nevi of special sites. Clin Lab Med. 2011;31(2):229-242.