Atypical melanocytic nevi of genital type: a distinctive pigmented lesion of the genital tract often confused with malignant melanoma.

A 30-year-old female presented with a 0.3 cm slightly raised tan-brown papule with somewhat irregular borders on her right labia minora. The papule was detected by her gynecologist during an annual gynecologic visit. Excision of the lesion revealed an atypical melanocytic nevus of genital type (AMNGT). This nevus is often confused with other pigmented lesions especially dysplastic nevus or even malignant melanoma. This distinctive melanocytic nevus often causes significant concern to pathologists and dermatologists. The diagnostic criteria and differentiating features from dysplastic nevi and malignant melanoma are discussed.