Recurrent / persistent nevi
Persistent nevi, also called recurrent nevi or pseudomelanoma, are defined as recurrences of pigmentation that appear after incomplete removal of a compound or intradermal melanocytic nevus.
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-pathology is available, but not always.
The challenge for the clinician is how to deal with this situation to find the correct diagnosis and the best treatment for the patient.
Based on a study of the International Dermoscopy Society (IDS) following recommendations could be the base for a helpful clinical and dermoscopic approach (1).
Clinical approach
Based on the history (age of patient and time period to the former procedure) following helpful differentiation could be done between a recurrent nevus and a recurrent melanoma:
| Recurrent nevus | Recurrent melanoma | |
|---|---|---|
| Age of patient | < 30 years1 | > 30 years1 |
| Time period of recurrent pigmentation | Short2 | Long2 |
130 vs. 63 years 28 vs 26 months
Dermoscopic approach
Based on the dermoscopic features following helpful differentiation could be done between a recurrent nevus (Figure 1) and a recurrent melanoma (Figure 2):
| Recurrent nevus (Figure 1) | Recurrent melanoma (Figure 2) |
|---|---|
| Radial lines | Pigmentation around the hair follicles ("circles") (face) |
| Symmetry | Eccentric hyperpigmentation |
| Centrifugal growth | Chaotic-like growth |
| Non-continuous growth | |
| pigmentation beyond the scar
(strongest indicator in the statistical analysis (1)) |
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 skin.
Recommendation
- 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 criteria 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 dermoscopy nearly symmtrical radial lines with centrigual growth inside the scar are visible.
Fig 2: Recurrent melanoma of a 72-year-old male after excision of a lentigo-maligna-melanoma at the face after 30 months. In dermoscopy pigmentation around the hair follicles ("circles"), eccentric hyperpigmentation and pigmentation beyond the scar are visible.
- ↑ 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.
