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Synchronous Melanomas Within Nevus Spilus

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Dear Editor ,

Nevus spilus (NS), also known as speckled lentiginous nevus, is a hyperpigmented macule or patch with superimposed darker speckles that usually appears in infancy or childhood.

It corresponds to a focal proliferation of melanocytes along the basal layer of the epidermis within a lentiginous background. The speckles display the histological features of different type of nevi such as junctional, intradermal, dysplastic, Spitz and blue nevus. NS can be divided into 3 categories regarding its dimension: small if >1.5 cm, medium from 1.5 to 19.9 cm and large if >20 cm [ 1 , 2 ] .

The possible occurrence of melanoma within the nevus has been described in literature in about 40 cases to date, usually in patients aged around 50 years [ 3 , 4 ] . The presence of NS since birth, the dimension over 4 cm in diameter, the giant or zosteriform type are associated with higher risk to develop melanoma [ 4 ] . The frequency of this transformation is significant, but it appears to be lower than congenital nevi of the same size [ 4 ] .

Herein we report the case of a 72-year-old male with 2 melanomas within a NS. He came to our department for his first skin examination, there was no personal or family history of skin cancers. On the right upper quadrant of the abdomen, we noticed a 5.5×1.8 cm speckled lentiginous nevus with a small hyperpigmented slightly palpable lesion measured 6×5mm. Dermoscopy showed within the lentiginous background a reddish area and an irregular pigmented network with some peripheral streaks (suggestive of melanoma) and comedo-like openings in the center (suggestive of seborrheic keratosis).

Histological analysis of the biopsied sample revealed a superficially spreading melanoma with a Breslow thickness of 0.3mm (pT1a) with lichenoid regression and acanthosis. A further surgical excision was carried out with the complete removal of the NS. In the new skin sample an in-situ melanoma outbreak was also found. Dermatological follow-up is now performed every 6 months.

NS can be seen as a “melanocytic garden” in which different lesions can grow based on the melanocyte differentiation pathway. Up to date, NS is usually not considered as a precursor of melanoma nevertheless, his malignant potential is described in literature. In the reported few cases of melanoma the most common types of melanoma were superficially spreading melanoma (68%) and nodular melanoma (16%), in rare cases also melanoma in situ. Our case confirms the presence of the most frequent histotype, but also highlights the occurrence of synchronous melanoma in situ. Only 4 cases of synchronous melanomas within a NS are reported [ 3 6 ] ( Table 1 ).

Dermoscopically, in our case the presence of melanoma was also partially hidden by seborrheic keratosis features, however considering the possibility of melanoma within a NS a biopsy was necessary to solve the diagnostic problem.

Changing pigmented areas or nodules require selective biopsy for histological examination. In the case of a positive histological test, a complete excision of the entire NS is required, in order to search for any multifocal melanomas such as in our case.

References

  1. Nevus Spilus: A Review of the Literature Corradin MT, Cacitti V, Giulioni E, Patriarca MM, Vettorello A. SM Dermatology Journal.2015;1(1):1-7.
  2. Nevus spilus and melanoma: Case report and review of the literature Corradin MT, Zattra E, Fiorentino R, Alaibac M, Belloni-Fortina A. J Cutan Med Surg.2010;14(2):85-89. CrossRef PubMed
  3. Synchronous melanomas arising within nevus spilus Brito MH, Dionísio CS, Fernandes CM, Ferreira JC, Rosa MJ, Garcia MM. An Bras Dermatol.2017;92(1):107-109. CrossRef PubMed
  4. Mélanome sur naevus spilus: 5 observations [Melanoma within naevus spilus: 5 cases] Abecassis S, Spatz A, Cazeneuve C, et al. Ann Dermatol Venereol.2006;133(4):323-328. CrossRef PubMed
  5. Nevus spilus with synchronous melanomas: case report and literature review Meguerditchian AN, Cheney RT, Kane JM. J Cutan Med Surg.2009;13(2):96-101. CrossRef PubMed
  6. Multifocal melanoma arising on nevus spilus Piana S, Gelli MC, Grenzi L, Ricci C, Gardini S, Piana S. Int J Dermatol.2006;45(11):1380-1381. CrossRef PubMed

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