| • | includes "nevus depigmentosus" and "hypomelanosis of Ito" |
| • | but "Nevoid Hypopigmentation" '“with” or “without" "extracutaneous abnormalities” are better terms |
Nevus Depigmentosus vs. Hypomelanosis of Ito:
| • | same histology; both may present after birth |
| • | ND more stable; Ito may progress or regress |
| • | Orlow says difference is semantic |
Work-up:
| • | data from a large study indicate that the time of onset of CNS symptoms in most patients is early (*usually before 2 years of age) |
| • | and either precedes or is coincident with the onset of skin findings |
| • | in addition, analysis of the data from several studies indicates that most patients at risk for neurological problems display additional overt clinical features that clearly indicate extracutaneous involvement |
| • | for instance: abnormal facies, limb asymmetries, and scoliosis |
| • | therefore, an extensive workup including neurologic and imaging studies, is probably not necessary in a child with linear hypopigmentation who appears normal and otherwise healthy, especially if he or she is over 2 years of age |
| • | pediatric neurologic and ophthalmologic exams |
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Nevus Depigmentosus
| • | should be called “nevus hypopigmentus” |
| • | a common birthmark (1 in 125) |
| • | usually as single, well demarcated hypomelanotic macule ranging in size from 0.5 to 10cm |
| • | less often, the distribution will be segmental or systematized (multiple streaks along the lines of Blaschko) |
histology:
| • | decreased to normal number of melanocytes |
ddx:
| • | vs. nevus anemicus (ND boundary does not disappear with diascopy) |
| • | vs. ash leaf of tuberous sclerosis: |
| • | can have the same clinical and histologic appearance |
| • | if a single lesion and asymptomatic, then watch |
| • | if multiple lesions or symptoms of tuberous sclerosis, then diagnostic imaging |
Hypomelanosis of Ito
| • | ddx = systematized nevus depigmentosus |
| • | sporadic; Blashko’s lines |
| • | histology: decreased melanin, normal or decreased # of melanocytes |
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