Linear and whorled nevoid hypermelanosis in Child
In the minority of cases, associated anomalies have been detected involving the central nervous and musculoskeletal systems as well as ocular and other abnormalities.
This disorder most likely represents a mosaic population of neuroectodermal cells, resulting in 2 distinct populations of skin cells having different colors.
Both the pigmentary and systemic findings are thought due to genetic mosaicism, with mutations in various genes leading to the variety of phenotypes observed. Mosaicism for c-KIT ligand (KITLG) in the hyperpigmented affected skin has been detected in one well-studied case.
L81.8 – Other specified disorders of pigmentation
403803002 – Linear and whorled nevoid hypermelanosis
Differential Diagnosis & Pitfalls
- Incontinentia pigmenti (IP) – The third stage of IP shows hyperpigmented streaks in a Blaschko-like pattern, though typically there are preceding vesiculobullous and verrucous stages. IP is lethal in males due to an X-linked dominant inheritance. The mother should be examined.
- Hypomelanosis of Ito (HI) – Typically presents at or soon after birth with hypopigmentation along lines of Blaschko, though there may concurrent hyperpigmentation. HI is also associated with extracutaneous anomalies.
- Linear epidermal nevus
- Albright syndrome