Linear morphea-induced atrophy treated with hyaluronic acid filler injections.

Linear morphea in an en coup de sabre pattern is a variant of localized scleroderma that develops on the frontal or frontoparietal scalp. Approximately two-thirds of cases occur before the age of 18. The etiology is unknown, but the disease is thought to be most likely autoimmune in nature. Between 50% and 75% of these patients have been found to have a positive serum antinuclear antibody (ANA), although ANA positivity has not been noted to correlate with disease activity. In en coup de sabre morphea, trauma has also been cited as a possible trigger. Although lesions may be limited to the skin, en coup de sabre morphea is notorious for extracutaneous involvement, and lesions may extend deep into underlying tissues and may be associated with neurologic, ophthalmologic, and oral abnormalities.