From the Guidelines
The cutaneous manifestations associated with anti-synthetase syndrome, a type of idiopathic inflammatory myopathy (IIM), primarily include mechanic's hands and Raynaud's phenomenon. These manifestations are characterized by hyperkeratotic, fissured, and cracked skin on the lateral and palmar aspects of the fingers and hands, giving them a rough, dirty appearance despite washing, and episodic color changes in the fingers and toes in response to cold or stress, respectively. Other skin findings may include various rashes, although the specific types are not as commonly associated with anti-synthetase syndrome as they are with other forms of IIM, such as dermatomyositis. The skin findings result from underlying autoimmune inflammation directed against aminoacyl-tRNA synthetases, with Jo-1 being the most common antibody, as noted in 1. Early recognition of these cutaneous signs is crucial as they may precede muscle or lung involvement and can help establish diagnosis and initiate appropriate immunosuppressive therapy before organ damage progresses. Some studies, such as 1, discuss treatments for skin manifestations in other autoimmune diseases, but the primary concern in anti-synthetase syndrome remains the identification and management of its distinct cutaneous features, which are directly related to the autoimmune process targeting aminoacyl-tRNA synthetases. The assessment of skin disease in patients with IIM can be facilitated by tools like the Cutaneous Assessment Tool, as mentioned in 1, highlighting the importance of monitoring skin activity and damage in the management of these conditions. However, the specific cutaneous manifestations of anti-synthetase syndrome, such as mechanic's hands and Raynaud's phenomenon, are key to its diagnosis and differentiation from other forms of IIM.
From the Research
Cutaneous Manifestations of Anti-Synthetase Type of Idiopathic Inflammatory Myopathy
The anti-synthetase type of idiopathic inflammatory myopathy is characterized by several cutaneous manifestations, including:
- Mechanic's hands: a characteristic cutaneous sign of antisynthetase syndrome, presenting as scaly, fissured, hyperkeratotic lesions on the lateral and palmar surfaces of the fingers 2, 3, 4, 5, 6
- Hyperkeratotic skin changes: often seen in patients with antisynthetase syndromes, particularly those with anti-glycyl-tRNA synthetase (anti-EJ) autoantibodies 5
- Psoriasiform tissue reaction: observed in finger lesions clinically diagnosed as mechanic's hands in patients with antisynthetase syndrome 6
- Skin lesions: may be a marker of visceral involvement and should be sought in any instance of suspected antisynthetase syndrome flare-up 2
Characteristics of Cutaneous Manifestations
The cutaneous manifestations of anti-synthetase type of idiopathic inflammatory myopathy have several characteristics, including:
- Mechanic's hands are a key indicator in cases of antisynthetase syndrome and its outcome is intimately linked with underlying systemic involvement, particularly pulmonary 4
- Cutaneous signs may regress totally or partially in all patients under treatment, but worsening can be seen during systemic episodes of the disease 4
- The presence of mechanic's hands does not vary according to antibody type 4