Speckled lentiginous nevus syndrome is a rare neurocutaneous phenotype, characterized by a specked lentiginous nevus, appearing as a light brown macule superimposed by multiple melanocytic nevi in the form of macules or papules with uneven distribution, associated with ipsilateral neurological and musculoskeletal abnormalities (i.e., dysesthesia, hyperhidrosis, and musculoskeletal abnormalities) occur. It represents a mosaic phenotype disorder resulting from postzygotic loss of heterozygosity, due to a localized defect in neural crest melanoblasts that originate certain areas of the skin and some ipsilateral neurological and musculoskeletal cells. Environmental and genetic factors may also play a role, but it has not been clarified how these factors behave in this syndrome.