En coup de sabre is a type of linear scleroderma characterized by a linear band of atrophy and a furrow in the skin that occurs in the frontal or frontoparietal scalp. Multiple lesions of en coup de sabre may coexist in a single patient, with one report suggesting that the lesions followed Blaschko lines . Unlike skin in localized morphea, skin in linear scleroderma may be fixed to underlying tissue. Calcinosis may rarely occur. Cutaneous changes accompanying the facial hemiatrophy associated with the Parry-Romberg syndrome may be similar to those found in en coup de sabre . Serologic abnormalities may include anti-nuclear antibodies, anti-single-stranded DNA antibodies, and rheumatoid factor. Eosinophilia may be present and may correlate with disease activity. A polyclonal IgG and IgM hypergammaglobulinemia may also be present and is found more often with severe cases and with clinical progression .
On the basis of a retrospective analysis of patients who developed morphea between 1960 and 1993 in Olmsted County Minnesota, the incidence of en coup de sabre is 0.13 cases per 100,000 population . Of the 82 cases of morphea identified in that study, 16 patients had linear scleroderma, including 4 with en coup de sabre and 2 with Parry-Romberg syndrome. None of these patients developed systemic sclerosis, although progression from linear scleroderma to systemic disease has been reported. Skin softening or disease resolution occurred in 8 of 16 patients within 5 years of diagnosis.
As in other types of scleroderma, the etiology of en coup de sabre is unknown. Hypotheses include microchimerism, which leads to a chronic, low-grade graft-versus-host-like disease, or an alteration in antigens caused by ischemic damage . Borrelia burgdorferi DNA has been identified by polymerase chain reaction assays in tissue sections from some, but not all, patients with localized scleroderma.
Modalities used in the management of en coup de sabre have included topical, intralesional, or systemic glucocorticoids; vitamin E; vitamin D3; phenytoin; retinoids; penicillin; griseofulvin; interferon-(x), D-penicillamine; antimalarials; ultraviolet A phototherapy with or without psoralens; and surgery .
