Recurrent nevi, also called persistent nevi, are pigmented skin lesions that clinically, dermoscopically and also histopathologically are commonly misinterpreted as melanoma in situ or superficial melanoma. Recurrent nevi are rather frequently observed following incomplete excision by superficial shaving techniques, an ordinary procedure for the management not only of dermal but also of Clark nevi in the daily routine of a busy dermatologic out-patient service. Due to the incomplete excision of these nevi, melanocytes/nevus cells may persist at the edge of the lesion as well as in the depth thus proliferating locally and reappearing as an irregular hyperpigmentation in the scar within a few weeks.
Recurrent nevi usually appear as asymmetric, bizarrely outlined and poorly circumscribed patches with a dark-brown to black pigmentation resembling a superficial melanoma. As a rule, a scar is present around this pigmented lesion, although in some instances the scar is difficult to detect and only anamnestic data lead to the diagnosis of recurrent nevus [Park 1987]. Obviously, the most important differential diagnosis is recurrent/persistent melanoma and, at least in our opinion, re-evaluation of the original histopathologic specimen is mandatory for a definite diagnosis [Kornberg and Ackerman 1975].
Dermoscopically, recurrent nevi are usually characterized by the presence of a homogeneous or multicomponent pattern with a prominent dark-brown to black coloration. An atypical pigment network, irregular streaks and black dots are commonly observed in recurrent nevi [Marghoob 1997]. In our view, the dermoscopic features of recurrent nevi are quite characteristic, although we did not have the opportunity to study the dermoscopic features of recurrent/persistent melanoma. Therefore, complete surgical excision and subsequent histopathologic examination of a recurrent nevus is strongly recommended in order not to overlook a recurrent/persistent melanoma.