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]
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. 
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,  adult-onset hearing loss, corneal snowflake 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. [6, 7]
Speckled lentiginous nevus syndrome has been characterized as a distinct neurocutaneous phenotype where ipsilateral neurological abnormalities are present in association with speckled lentiginous nevus. [6, 7, 8, 9, 11, 12]
In the general 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. 
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 predilection is noted.
No sexual predilection is recognized.
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%.
Speckled lentiginous nevus is a benign neoplasm. In rare instances of malignant transformation within a speckled lentiginous nevus, morbidity and mortality are dependent on the stage of the secondary malignancy. At least 20 cases of cutaneous melanoma developing within a speckled lentiginous nevus have been reported. [14, 15, 16, 17, 18, 19]
Regular visits to a dermatologist and careful examination with the use of photography should be used for early recognition of atypical features within a speckled lentiginous nevus.