What is nevus spilus?
Nevus spilus (aka speckled lentiginous nevus) is a common cutaneous lesion.
"a circumscribed tan macule in which more darkly pigmented, raised, and/or flat melanocytic or nevomelanocytic elements are distributed."
Clinical presentationThe speckled lentiginous lesion is a lentigo simplex macule superimposed with melanocytic nevus. Though the NS may appear anywhere on the body, its common locations are chest and upper limbs. Quite often the arrangement of the spilus lesion follows the lines of Blaschko.
The speckled lentiginous macules can be classified into three distinct clinical types. The macule is considered small, if it is less than 1.5 cm, medium if it is between 1.5 to 19.9 cm and large or giant if it exceeds 20 cm. There also exists segmental distribution of speckled lentiginous lesion, known as zosteriform nevus spilus. The number of speckles differs generally in relation to size of the NS and in some cases up to 30 speckles have been recorded. The speckles usually range between one to three millimeters, though larger sizes have been recorded.
Histopathology and diagnosis of speckled lentiginous nevusThe early spilus lesion in its non-spotted form appears similar to café au lait spot. Though the tan background of speckled lentiginous lesions appears similar to the café au lait spot, they are separate entities clinically and histologically. The speckled lentiginous lesions consistently have been shown to contain nevus cells, which are large variations of typical melanocytes, lacking dendrites and having more abundant cytoplasm with coarse pigment granules. Though the presence of nevus cells in the café au lait spot had been recorded in some studies, there are no records of the presence of speckles within these café au lait spots.
The speckled lentiginous nevus has similarity in appearance to agminated lentigines. Agminated lentigines may be present at birth or form in early childhood. Agminated lentiginosis is an unusual pigmentary disorder, characterized by numerous pigmented spots grouped within an area of normal skin. The distinguishing feature of agminated lentiginosis is that it appears on a normal skin whereas speckled lentiginous spilus appears on a tan-brown skin.
Histologically, the light tan-brown background patch of nevus usually shows mild hyperplasia of melanocytes. The speckled lentiginous spilus also shows features of lentigo simplex, including the elongation of rete ridges (epidermal thickenings that extend downward between dermal papillae) and increase in the concentration of basal layer melanocytes. Nevus spilus also shows increase in melanin concentration and number of melanosomes present in the melanocytes, basal keratinocytes and dermal melanophages. Junctional nests of melanocytes are seen in the hyperpigmented speckled lentiginous spilus spots.
Malignant melanoma and nevus spilusIn very rare cases the speckled lentiginous spilus had turn into a malignant melanoma. Maria Teresa Corradin et al. reported a case of a pre-existing spilus in NS turning into malignant melanoma in an 80-year-old male patient. They inferred that
"The risk factor of malignant transformation seems to increase when the lesion is congenital or acquired in infancy, when its size is ≥ 4 cm, and when the type of NS is macular rather than papular".There are recent observations of malignant melanoma developing within the lesions and a few fatal cases have been reported. The risk of developing melanoma in the NS is increased if NS is present at birth, is more than 4 cm, is of giant form or is of zosteriform.
Speckled lentiginous nevus and complications
- FACES syndrome is a syndrome of unique facial features, anorexia, cachexia, eye and skin anomalies. Some cases of speckled lentiginous spots are associated with FACES syndrome.
- The birth defect, phacomatosis pigmentovascularis is associated with macular nevus spilus.
- The complex birth defect phacomatosis pigmentokeratotica is associated with papular speckled lentiginous spots.
- "Speckled lentiginous nevus syndrome, a recently recognized phenotype is characterized by a speckled lentiginous nevus of the papular type and ipsilateral neurological abnormalities in the form of dysesthesia, muscular weakness or hyperhidrosis".
Nevus spilus treatment and managementCases of nevus spilus transformation into melanoma requires excision to prevent recurrence and eliminate the source fields. However the aggressive treatment may leave a permanent scar. So this option may be exercised when there is clear evidence of melanoma. The Q-switched ruby or Q-switched Nd:YAG lasers are useful in treating both the background hyperpigmentation and the hyperpigmented spots. Treating nevus spilus with laser therapy had showed good clinical clearance with enhanced cosmetic effect. But the threat of speckled lentiginous lesions transforming into melanoma always exists, requiring periodic evaluation.
1.Vidaurri-de la Cruz H, Happle R. Two distinct types of speckled lentiginous nevi characterized by macular versus papular speckles. Dermatology. 2006;212:53-58.
2.Abecassis S, Spatz A, Cazeneuve C, et al. Melanoma within nevus spilus: 5 cases [in French]. Ann Dermatol Venereol. 2006;133:323-328.
3.Kar H, Gupta L. Treatment of nevus spilus with Q switched Nd:YAG laser. Indian J Dermatol Venereol Leprol 2013;79:243-5.
4.Vente C, Neumann C, Bertsch H, Rupprecht R, Happle R. Speckled lentiginous nevus syndrome: report of a further case. Dermatology. 2004;209(3):228-9.
5.Vaidya DC, Schwartz RA, Janniger CK. Nevus spilus. Cutis. 2007 Dec;80(6):465-8.
6.Corradin, M. T., Giulioni, E., Fiorentino, R., Santeufemia, D. A., Re, G. L., & Vettorello, A. (2014). In situ malignant melanoma on nevus spilus in an elderly patient. Acta dermatovenerologica Alpina, Panonica, et Adriatica, 23(1), 17-19.