This linear pattern of hyper-pigmented, often verrucous tissue oriented along Blaschko skin lines is typical for linear epidermal nevi (LEN). In some cases, lesions are not in a linear pattern and are actually in more of a localized or whorled pattern (called epidermal nevi).
LEN are usually present at birth, as in this individual. They are frequently seen on the head and neck region and are often asymptomatic. LEN are considered a birthmark that develops because of a genetic abnormality that typically affects keratinocytes. This genetic mutation only affects a portion of the body (mosaicism) without affecting the overall genetics of the individual. This is important to note because LEN do not typically have a hereditary component or implications for offspring. While usually asymptomatic and localized, LEN can be associated with extracutaneous and neurologic difficulties. In these situations, it is called epidermal nevus syndrome, and is more common if the LEN occur on the face or head.1
Since LEN are usually asymptomatic, treatment is not required unless the lesions affect the function of adjacent structures, such as the eyes, lips, or nose. Due to their frequent presence on the face or other visible areas, some patients may choose to get these lesions treated for cosmetic purposes. In the past, full-thickness excision was recommended. Topical medications are ineffective, and superficial shave excision usually leads to recurrence. More recently, destructive laser treatments have been used, with success, to reduce the appearance of the lesions.2
This patient was not concerned about the appearance of the asymptomatic lesions and chose not to have any treatment.
Photo and text courtesy of Daniel Stulberg, MD, FAAFP, Professor and Chair, Department of Family and Community Medicine, Western Michigan University Homer Stryker, MD School of Medicine, Kalamazoo.