Recurrent / persistent nevi
Authored by: Ashfaq A. Marghoob
Persistent neviThis glossary term has not yet been described., also called recurrent nevi or pseudomelanoma, are defined as recurrences of pigmentation that appear after incomplete removal of a compound or intradermal melanocyticThis glossary term has not yet been described. nevusThis glossary term has not yet been described..
Most theories suggest that persistent nevi arise from residual nevomelanocytes found in hair follicles, sweat glands, dermis, or epidermis.
In daily practice patients present a repigmentation in a scar after any former procedures as excision, shave excision, laser treatment or injury. In some cases a report of histo-pathologyThis glossary term has not yet been described. is available, but not always.
The challenge for the clinician is how toGives basic instructions and directions to someone on the methods for doing or making something. deal with this situation to find the correct diagnosisis the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines with variations in the use of logic, analytics, and experience to determine "cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions and the best treatment for the patient.
Based on a study of the International DermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections. Society (IDSIDS stands for the International Dermoscopy Society.) following recommendations could be the base for a helpful clinical and dermoscopic approach (1).
Based on the history (ageprocess of becoming older of patient and time period to the former procedure) following helpful differentiation could be done between a recurrent nevus and a recurrent melanomaThis glossary term has not yet been described.:
|Recurrent nevus||Recurrent melanoma|
|Ageprocess of becoming older of patient||< 30 years1||> 30 years1|
|Time period of recurrent pigmentation||Short2||Long2|
28 vs 26 months
Based on the dermoscopic features following helpful differentiation could be done between a recurrent nevus (Figure 1) and a recurrent melanoma (Figure 2):
In recurrent nevi the appearance of the pigmentation usually develops within three to six months.
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 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..
- When the first histo-pathology revealed a severe melanocytic dysplasia, an in-situ or invasive melanoma then perform a complete excision with histo-pathology of any recurrent pigmentation in the scar, independently of the dermoscopic features.
- When a re-pigmentation occured in a scar of an unknown tumor, no histo-pathology is available and the clinical and dermsocopic criteriameasure of how well one variable or set of variables predicts an outcome exclude a recurrent melanoma then perform a follow-up in 2-3 months. Also confocal laser microscopy could be used to differentiate between a recurrent nevus and a recurrent melanoma (2,3).
Fig 1: Recurrent nevus of a 26-year-old female after shave excision of a benig nevus at the trunk after 6 months. In dermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections. nearly symmtrical radial lines with centrigual growth inside the scar are visible.
ReferencesThis is material contained in a footnote or bibliography holding further information.: 
- An Atlas of Dermoscopy, Second Edition. Marghoob A. et al. CRC Press; 2012.
- Blum A, Hofmann-Wellenhof R, Marghoob AA, et al. (2014) Recurrent Melanocytic Nevi and Melanomas in Dermoscopy: Results of a Multicenter Study of the International Dermoscopy Society. JAMA Dermatol 1;150(2):138-145.
- Larre Borges A, Zalaudek I, Longo C, et al. (2014) Melanocytic nevi with special features: clinical-dermoscopic and reflectance confocal microscopic-findings. J Eur Acad Dermatol Venereol 28(7):833-45.
- Cinotti E, Labeille B, Debarbieux S, et al. (2018) Dermoscopy vs. reflectance confocal microscopy for the diagnosis of lentigo maligna. J Eur Acad Dermatol Venereol 2018 Jan 17. doi: 10.1111/jdv.14791.