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Mechanic's hands lesions in antisynthetase syndrome.

A 46-year-old man presented with gradually worsening chronic dry cough and shortness of breath for over 2 years. He was initially evaluated at an outside hospital and treated with oral prednisone and continuous supplemental oxygen. Physical examination revealed velcro rales in bilateral lung fields and mechanic’s hands (Figure 1a). Pulmonary function tests were suggestive of restrictive lung disease (FEV1/FVC: 85%, DLCO 36%). Serum creatine kinase and aldolase levels were elevated. Further workup revealed a positive AntiJo-1 antibody. Highresolution chest computerized tomography showed a pattern consistent with usual interstitial pneumonia (Figure 1b, arrowheads). He met criteria for antisynthetase syndrome and was initiated on treatment with mycophenolate and prednisone. He currently awaits lung transplantation evaluation. Antisynthetase syndrome is a systemic autoimmune syndrome characterized by inflammatory myopathy, arthritis or arthralgias, interstitial lung disease (ILD), fever, Raynaud’s phenomenon and mechanic’s hands. It is strongly associated with autoantibodies to aminoacyl-transfer RNA synthetases like anti–Jo-1. Incidence of mechanic’s hands in antisynthetase syndrome is between 20 and 70%. Mechanic’s hands typically appear as well-demarcated hyperkeratotic and nonpruritic erythema on the radial and palmar aspects of the hands and fingers. The histopathological findings include marked hyperkeratosis, focal parakeratosis, psoriasiform acanthosis, colloid bodies in the epidermis and mononuclear cell infiltrates around the blood vessels in the upper dermis and epidermis. A close differential diagnosis of mechanic’s hands is eczema. However, unlike eczema, mechanic’s hand typically does not have associated pruritus, lesions are usually bilateral and symmetric, whereas in hand eczema, they are often observed in the dominant arm. Among patients with antisynthetase syndrome, mechanic’s hands and interstitial pneumonia coexist in around 70% of cases. In a patient with an established diagnosis of antisynthetase syndrome, new appearance of mechanics hands may herald new deep tissue involvement, e.g. interstitial pneumonia. Resolution of mechanic’s hand lesions have been found to often correlate with improvement in deep tissue involvement. The prognosis in antisynthetase syndrome is primarily dependent on the severity of pulmonary involvement, and the earlier diagnosis of ILD leads to better outcomes. Hence, early recognition of mechanic’s hand lesions might help in early detection of ILD in patients with antisynthetase syndrome.