Mechanics hands in patients with antisynthetase syndrome: 25 cases

Antisynthetase antibodies (ASA) are directed against aminoacyl-tRNA-synthetases, ubiquitous enzymes of which eight types have hitherto been described. They are seen primarily in antisynthetase syndrome (ASS), in which diffuse interstitial lung disease is associated with inflammatory myopathy, joint involvement and cutaneous signs, in particular mechanic's hands. The aim of this study was to determine the prevalence and semiological characteristics of cutaneous involvement in patients presenting ASA.

We carried out a retrospective study of the medical files of patients with ASA diagnosed at the Strasbourg University Hospital between 1994 and 2009.

We identified 22 women and 3 men presenting ASS (n=21), dermatomyositis (n=3) or sclerodermatomyositis (n=1). Mean age at the time of diagnosis was 56 years (12-79). The most commonly seen antibodies were anti-Jo1 (n=19), with the other cases of ASA involving anti-PL12 (n=3), anti-PL7 (n=2) and anti-EJ (n=1) antibodies. Five patients died from pulmonary complications. Mechanic's hands (characteristic plaques and papules along the edge of the first fingers on both hands) were found in 10 patients with ASS (7 cases) or dermatomyositis (3 cases), at the time of diagnosis in 7 cases and during a systemic episode in 3 cases. Muscular involvement was seen in all patients: 9 had diffuse interstitial lung disease and 8 had joint involvement. Cutaneous signs regressed totally or partially in all patients under treatment; in 6 patients, worsening was seen during systemic episodes of the disease. One of the 10 patients died through pulmonary complications.

Mechanic's hands are a key indicator in cases of ASA and its outcome is intimately linked with underlying systemic involvement, particularly pulmonary. The characteristic semiology enables this disorder to be recognised and allows differentiation from psoriasis or irritant contact dermatitis of the hands, and it does not vary according to antibody. Whether or not the disease is life-threatening is unaffected by the presence of this sign.