Recurrent / persistent nevi
Authored by: Ashfaq A. Marghoob
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User=Persistent neviThis glossary term has not yet been described., also called recurrent nevi or pseudomelanoma, are defi ned as recurrences of pigmentation that appear after incomplete removal of a compound or intradermal melanocyticThis glossary term has not yet been described. nevus (Harvell & White, 1999; Harvell et al., 2002; Sexton & Sexton, 1991). Many mechanisms have been proposed for the pathogenesis of these nevi; however, most theories suggest that persistent nevi arise from residual nevomelanocytes found in hair follicles, sweat glands, dermis, or epidermis (Sexton & Sexton, 1991). Although most persistent nevi arise after incomplete surgical removal, some can arise after laser treatment or after non–biopsy-related trauma to a melanocytic nevus (Langel & White, 2000). As the term “pseudomelanoma” implies, it may be difficultThis glossary term has not yet been described. to differentiate recurrent nevi from melanomaThis glossary term has not yet been described. at the clinical, dermoscopic, and histopathologic levels. Obviously, a history of a previous biopsy of a benignThis glossary term has not yet been described. nevus at the location of the now recurrent lesion is an important clue to the diagnosisThis glossary term has not yet been described. of a recurrent nevusThis glossary term has not yet been described.. In such scenarios it is important to review the original pathologyThis glossary term has not yet been described. slides to insure that the biopsied lesion was indeed benign. With that said, there are subtle differences that may enable one to distinguish between a recurrent nevus versus a recurrent melanoma. A historical clue is that in recurrent nevi the appearance of the pigmentation usually develops within three to six months (Park et al., 1987). In contrast, the pigment in locally recurrent melanomas characteristically becomes apparent after six months from the time of the biopsy; in fact, most recur years after the initial biopsy. In addition, in persistent nevi the pigment almost never extends beyond the scar (i.e., the pigment is usually confined to within the scar), whereas recurrent melanoma often manifests as a pigmented macule, papule, or nodule at the edge of a scar, frequently extending beyond the scar—extending onto normal uninvolved skinThis glossary term has not yet been described.. The dermoscopic features of persistent nevi include the following: asymmetry, sharp borders, homogenous or multicomponent patternThis glossary term has not yet been described., atypical pigment networkNetwork with increased variability in the color, thickness, and spacing of the lines of the network; asymmetrically distributed; gray color, irregular streakslines, radial (always at periphery) Reed nevus, melanoma, recurrent nevus, black dotsThis glossary term has not yet been described., globulesThis glossary term has not yet been described., and blue-gray or red colors (Marghoob & Kopf, 1997). It is not uncommon for the pigment of recurrent nevi to fade over time. The same dermoscopic features seen in persistent nevi can also be seen in primary melanoma. The dermoscopic features of local recurrent melanoma are described as globular or diffuse nonhomogenous pigmentation in the absence of a pigment network (Ferrari et al., 2000). However, pigment networkGrid-like pattern consisting of interconnecting pigmented lines surrounding hypopigmented holes., regressionThis glossary term has not yet been described. structures, crystalline structures, or other melanomaspecific structures can also be seen. In conclusion, it is often impossible to differentiate recurrent nevi from melanoma. As a general rule, in recurrent nevi the pigment will not extend beyond the white biopsy scar, the pigment will recur within three to six months from the time of the biopsy, the entire scar will often be surrounded by a light brown halo of pigment, and the pigment will often fade over time
- An Atlas of Dermoscopy, Second Edition. Marghoob A. et al. CRC Press; 2012.