Skin melanocytic tumor


Nevus spilus

Resident / Fellow Advisory Board: Caroline I.M. Underwood, M.D.
Syeda Qasim, M.D.
Sarah E. Gradecki, M.D.

Last author update: 28 March 2023
Last staff update: 28 March 2023

Copyright: 2021-2023,, Inc.

PubMed Search: Nevus spilus

Syeda Qasim, M.D.
Sarah E. Gradecki, M.D.
Page views in 2022: 720
Page views in 2023 to date: 2,537
Cite this page: Qasim S, Gradecki SE. Nevus spilus. website. Accessed September 21st, 2023.
Definition / general
  • Nevus spilus (NS) or speckled lentiginous nevus is a melanocytic lesion composed of small, dark macules or a combination of macules and papules within a larger but more lightly pigmented patch
  • First described by Burkley in 1842 as evenly pigmented patches, Ito and Hamado in 1952 were the first to use the term NS in speckled lesions
Essential features
  • Pigmented skin lesion, congenital or acquired, consisting of a large light tan patch with numerous superimposed small, dark brown macules or papules (J Cutan Med Surg 2010;14:85)
  • Can be seen anywhere on the body surface but the most common location is on the chest and upper limbs (Cutis 2007;80:465)
  • Not considered a precursor of melanoma but cases have been described in which melanoma arose in NS (Hautarzt 1996;47:759)
  • Speckled lentiginous nevus (SLN)
  • Nevus on nevus
  • Naevus sur naevus
  • Speckled nevus spilus
  • Spotty nevus
  • Zostriform speckled lentiginous nevus
ICD coding
  • ICD-10: I78.1 - nevus, nonneoplastic
  • Has no predilection for either sex but is slightly more common in individuals of Northern European descent (J Am Acad Dermatol 1995;32:957)
  • Most lesions are present at birth but they also may be noticed during infancy, childhood or adulthood
  • Prevalence varies from between 0.2% to 2.3% according to age groups and the prevalence is similar to the overall occurrence of a congenital nevus (Pediatr Dermatol 1992;9:345)
  • Can be seen anywhere on the body surface but the most common location is on the chest and upper limbs; lesions tend to follow lines of Blaschko (Arch Dermatol 1985;121:766)
  • Varies in size from 1 to 20 cm in diameter and may appear on any area of the face, trunk or extremities without relation to sun exposure (Dermatology 1994;189:382)
  • Unknown pathogenesis; some theories suggest a localized defect in neural crest melanoblasts (Arch Dermatol 2001;137:172)
  • Familial cases have not been reported but genetic factors may play a role
  • Mosaicism has been suggested to explain the zosteriform variant
  • Happle has suggested dividing NS into 2 entities, a macular type and a papular type
  • Unknown
Clinical features
  • Presents as a solitary, nonhairy, flat, brown patch dotted by smaller dark brown to black macules or papules (Cutis 2007;80:465)
  • Earliest findings are similar to a café au lait patch, with eventual development of the secondary superimposed darker melanocytic lesions (Arch Dermatol 2001;137:215)
  • Can be associated with a number of other conditions, including corneal dystrophy, scleral pigmentation, hearing loss, Ebstein anomaly, neurofibromatosis type 1, epidermal nevi and nevus sebaceus
  • Is a component of certain presentations of phakomatosis pigmentovascularis (J Am Acad Dermatol 2021 Feb 11 [Epub ahead of print])
  • Speckled lentiginous nevus syndrome is the rarely occurring association of NS (usually nevus spilus papulosis) and neuromuscular abnormalities, including a sensory or motor neuropathy and hyperhidrosis
  • Clinical presentation of NS, with a tan macule and speckled hyperpigmentation, is distinctive (Arch Dermatol 1970;102:433)
  • Rare cases may require a biopsy but it is critical to convey the clinical impression of NS by description or by an attached photograph, so that the pathologist or dermatopathologist can appreciate the asymmetric and sometimes subtle histologic findings (Indian Pediatr 2005;42:831)
Prognostic factors
  • Darker, smaller pigmented melanocytic components of NS have the potential to develop malignant melanoma, although the frequency of this transformation appears to be low
  • Melanoma may rarely occur in NS with an increasing incidence
  • Risk of developing melanoma in NS is increased if NS is congenital, > 4 cm in diameter or giant or zosteriform in morphology
Case reports
  • 4 year old boy with a light brown colored elliptical patch on left cheek adjoining the angle of lip (Indian Pediatr 2005;42:831)
  • 33 year old woman with a medium sized nevus spilus located on the neck, successfully treated with 4 sessions of pulsed dye laser (Dermatol Ther 2017;30:e12497)
  • 65 year old woman presenting with a nodular achromic melanoma that occurred within a nevus spilus on the left thigh (J Cutan Med Surg 2010;14:85)
  • Patients should be followed regularly with clinical examination or photograph and with biopsy or excision of changing or clinically atypical areas
  • Cosmetically, laser treatment of nevus spilus has not been promising (Pediatr Dermatol 1998;15:407)
Clinical images

Contributed by Sarah E. Gradecki, M.D.
Light tan patch

Light tan patch

Gross description
  • Light tan patch of variable size with numerous superimposed small, dark brown, well circumscribed macules or papules
Microscopic (histologic) description
  • Flat, tan background may show only basilar hyperpigmentation, such as is present in café au lait spots, or lentiginous proliferation of the epidermis with bulbous rete ridges
  • Greater degree of pigmentation is linked to an increase in the number of melanocytes in the basal layer, as well as an increase in melanin content of the basal keratinocytes
  • Darker macules and papules seen clinically usually contain melanocytes, which can take the form of various types of nevi including junctional, compound, intradermal, dysplastic / atypical, blue or Spitz nevi (Cutis 2007;80:465)
Microscopic (histologic) images

Contributed by Sarah E. Gradecki, M.D.
Normal melanocytes

Normal melanocytes

Junctional melanocytic nevus Junctional melanocytic nevus

Junctional melanocytic nevus

Basilar hyperpigmentation

Basilar hyperpigmentation

Molecular / cytogenetics description
  • NS is postulated to result from a postzygotic genetic alteration of the melanocytic lineage, giving rise to a clone of melanocytes predisposed to developing a neoplasm; an activating clonal point mutation in HRAS has been identified in agminated Spitz nevi arising in a nevus spilus (JAMA Dermatol 2013;149:1077)
  • The same HRAS mutation has been identified in 8 additional sporadic NS, suggesting that the HRAS mutation is the predominant causative mutation for NS; this mutation is sufficient to cause activation of the MAPK pathway (J Invest Dermatol 2014;134:1766)
Sample pathology report
  • Skin, left chest wall, excision:
    • Lentiginous junctional melanocytic nevus (see comment)
    • Comment: Sections show alternating areas of lentiginous junctional melanocytic nevus and areas more consistent with lentigo. In the correct clinical context, the findings could be compatible with a diagnosis of nevus spilus.
Differential diagnosis
  • Melanoma:
    • Histological features including asymmetry, ulceration, cytological atypia, pagetoid involvement of the epidermis, lack of maturation and dermal mitoses including deep and atypical forms
  • Congenital nevus:
    • May be junctional, compound or dermal
    • Extension of nevus cells around nerves, vessels and adnexal structures is characteristic
  • Blue nevus:
    • Bipolar spindled dendritic melanocytes associated with variable amounts of dense collagenous stroma
  • Spitz nevus:
    • Well circumscribed and symmetrical with an overall wedge shaped silhouette
    • Consists of large junctional and dermal melanocytic nests formed by spindled or epithelioid cells
Additional references
Board review style question #1

Which of the following is a feature of nevus spilus?

  1. Absence of rete ridges
  2. Absence of significant pleomorphism of melanocytes
  3. Intradermal melanocytic proliferation
  4. Lack of basilar hyperpigmentation
Board review style answer #1
B. Absence of significant pleomorphism of melanocytes. Nevus spilus can be associated with moderate acanthosis, elongation of rete ridges and lentiginous proliferation of basal melanocytes at the dermoepidermal junction with hyperpigmentation of basal keratinocytes but not significant pleomorphism unless in rare cases the lesion progresses to melanoma.

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Reference: Nevus spilus
Board review style question #2
Which of the following is known to be associated with nevus spilus?

  1. Arnold-Chiari malformation
  2. Carcinomatosis
  3. Down syndrome
  4. Neurofibromatosis type 2
  5. Phakomatosis pigmentovascularis
Board review style answer #2
E. Phakomatosis pigmentovascularis. Nevus spilus can be associated with other conditions including phakomatosis pigmentovascularis, corneal dystrophy, scleral pigmentation, hearing loss, Ebstein anomaly, neurofibromatosis type 1, epidermal nevi and nevus sebaceus.

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Reference: Nevus spilus
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