Speckled Lentiginous Nevus 

Updated: Mar 02, 2022
Author: Rossitza Lazova, MD; Chief Editor: Dirk M Elston, MD 

Overview

Practice Essentials

Speckled lentiginous nevus is a patch of hyperpigmentation that can be seen on any area of the body. This patch contains a variable number of darkly pigmented macules and papules. Some authorities believe that speckled lentiginous nevus is a subtype of congenital melanocytic nevus.[1, 2, 3]

Patients may complain of hyperpigmented or multicolored skin lesions, with colors most often including shades of tan, brown, and black. The lesions are present at birth or noted during the individual's first years of life. Patients may be aware of an increase in the size of the lesions or changes in color over time. Skin distribution varies, with the trunk being the most common site of occurrence. It has also been reported in the oral cavity.[4]

Speckled lentiginous nevus may represent a localized defect in neural crest melanoblasts that populate a particular area of the skin. Environmental and genetic factors may also play a role. Mosaicism may be an explanation for the development of zosteriform speckled lentiginous nevus.[5]  

In its earliest stage, speckled lentiginous nevus can be confused with a café au lait macule. In agminated melanocytic nevi, the background skin is not hyperpigmented, unlike that in speckled lentiginous nevus. In partial unilateral lentiginosis, multiple lentigines are grouped together on skin that has a normal color. In India, trichrome vitiligo of the face developed in at least 1 case of congenital segmental speckled lentiginous nevus in a 9-year-old girl.[6]

Electron microscopic studies show melanosomes that are fully melanized and a few premelanosomes in junctional melanocytes.

Speckled lentiginous nevus is a benign neoplasm. Malignant melanoma may develop within speckled lentiginous nevus. Predictors of the risk of malignant transformation of a speckled lentiginous nevus have yet to be determined. The surface area, the number of nevi within the speckled lentiginous nevus, and/or the presence of cytologic atypia may be factors that affect the potential for malignant transformation of a speckled lentiginous nevus. At least 20 cases of cutaneous melanoma developing within a speckled lentiginous nevus have been reported. [7, 8, 9, 10, 11, 12]  In the rare instances where malignant transformation occurs within a speckled lentiginous nevus, morbidity and mortality are dependent on the stage of the secondary malignancy. 

Speckled lentiginous nevi are evaluated and treated with the same level of concern as would be warranted for congenital nevi of similar size. Biopsy is necessary to rule out cytologic atypia, which may develop in a speckled lentiginous nevus.

Regular visits to a dermatologist and careful examination with the use of photography are recommended for early recognition of atypical features within a speckled lentiginous nevus. Consult a dermatologist when diagnostic and/or therapeutic uncertainty exists regarding melanocytic neoplasms in general and speckled lentiginous nevus specifically.

Pathophysiology

Speckled lentiginous nevus can be associated with different disorders. In facial features, anorexia, cachexia, and eye and skin anomalies (FACES) syndrome, cutaneous findings include zosteriform speckled lentiginous nevi. Associated findings also include ichthyosis, Ebstein syndrome (the eponym for congenital downward displacement of the tricuspid valve into the right ventricle), epidermal nevi, nevus sebaceous, scleral pigmentation, segmental neurofibromatosis type I,[13] adult-onset hearing loss, granular corneal dystrophy, and hypertrophy of the underlying pectoralis major muscle. In addition, an association with abnormality of the tongue and median nerve paresis have been described.[14, 15]

An association with phacomatosis pigmentovascularis and phacomatosis pigmentokeratotica (PPK) has also been described.[16, 17, 18, 19, 20]  Loh et al present the case of a 52-year-old male with PPK and speckled lentiginous nevi on the left trunk and associated, multiple, biopsy-proven basal cell carcinomas.[21]  Om et al report a case of a pediatric patient with PPK and concomitant speckled lentiginous nevus who later developed vaginal botryoid rhabdomyosarcoma. The authors attributed the PPK onset to a novel ​KRAS mutation.[22]  Prieto-Barrios et al point out that activation of HRAS mosaic mutations can also cause PPK.[23]   

Speckled lentiginous nevus syndrome has been characterized as a distinct neurocutaneous phenotype where ipsilateral neurological abnormalities are present in association with speckled lentiginous nevus.[14, 15, 16, 17, 19]  This syndrome has been renamed as papular nevus spilus (PNS) syndrome to prevent confusion with macular nevus spilus. PNS syndrome is classified as a mosaic RASopathy, along with isolated nevus sebaceus, Schimmelpenning syndrome, and PKK.[24]

There has been at least a single pediatric case of PNS syndrome associated with musclar atrophy and motor neuropathy. The affected muscles were in an indentical distribution to the speckled lentiginous nevi.[25]

Epidemiology

In the general United States population, the prevalence of speckled lentiginous nevi is similar to that of congenital melanocytic nevi, with a prevalence of 0.2-2.3%, depending on age.[26]  Speckled lentiginous nevus has been studied in Canadian children of Asian and white European origins, and its prevalence is the same in both ethnic groups.

No racial or sexual predilections have been noted.

Low prevalence rates of up to 0.2% have been reported in series of newborns. Approximately 80% of speckled lentiginous nevi appear at birth or during early infancy. They may present as lightly-colored café au lait macules at birth, which later develop background hyperpigmentation and darkly pigmented macules and papules over months, years, or sometimes decades.

The prevalence rate of speckled lentiginous nevus is 1.3-2.1% in school-aged children and adolescents.

In adults, the frequency of speckled lentiginous nevi larger than 1.5 cm in diameter is 2.3%.

 

Presentation

Physical Examination

A variable number of black, brown, or red-brown macules and papules are seen within a patch of tan-to-brown hyperpigmentation. The background pigmented macule or patch is usually 3-6 cm in diameter, but the diameter may vary from 1 cm to more than 60 cm.

See the image below.

A large unilateral speckled lentiginous nevus that A large unilateral speckled lentiginous nevus that contains numerous small dark macules.

The lesions are usually oval, but they can be linear. Some follow the lines of Blaschko or have a sharp demarcation at the midline. An extensive amount of body surface area may be involved.

See the image below.

Extensive speckled lentiginous nevus. Extensive speckled lentiginous nevus.

The macules (speckles) and papules lying within the background patch range from lentigines to junctional, compound, or dermal nevi. Spitz nevi and blue nevi may also occur. The speckles range from 1-9 mm; most commonly, they are 2-3 mm in diameter. To the author's knowledge, deep penetrating nevus occurring within a speckled lentiginous nevus has not been reported.

 

DDx

 

Workup

Histologic Findings

Increased pigmentation in the basal layer of the epidermis and lentiginous epidermal hyperplasia are present in the background macule or patch of hyperpigmentation; these findings are similar to those of lentigo simplex. See the image below.

Prominent basal layer pigmentation similar to that Prominent basal layer pigmentation similar to that seen in lentigo simplex (hematoxylin-eosin stain, original magnification X200).

The number of melanocytes in these areas may be increased. Small nests of melanocytes are occasionally seen, and these are sometimes referred to as nevus incipiens. See the image below.

Elongated rete ridges and lentiginous proliferatio Elongated rete ridges and lentiginous proliferation of melanocytes at the dermal-epidermal junction (hematoxylin-eosin stain, original magnification X200).

Biopsy samples of the speckled regions show variable findings, including junctional lentiginous nevi, compound and intradermal nevi, as well as compound or intradermal nevi with congenital features.

See the images below.

Junctional melanocytic nevus composed of small nes Junctional melanocytic nevus composed of small nests of melanocytes and lentiginous melanocytic proliferation at the dermal-epidermal junction (hematoxylin-eosin stain, original magnification X100).
Compound melanocytic nevus with nests of uniform m Compound melanocytic nevus with nests of uniform melanocytes in the epidermis and the dermis (hematoxylin-eosin stain, original magnification X200).

Spitz nevi, blue nevi, and nevi with cytologic atypia (ie, dysplastic nevi) can also be seen. Collections of dermal melanophages without an inflammatory infiltrate are sometimes present.

 

Treatment

Surgical Care

Surgical removal is a therapeutic option for some patients. The entire area of hyperpigmentation must be excised to prevent recurrence because speckled lentiginous nevus represents a "field defect," ie, a defect in the melanoblasts that populate a localized area of the skin. Large scars can result.[27]

The Q-switched ruby or Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers have been used to treat both the background hyperpigmentation and the speckles of speckled lentiginous nevi. Results have not been promising from a cosmetic standpoint. Laser treatment of melanocytic nevi, including speckled lentiginous nevi, remains controversial.