Disclosures: Hanan Saleh, MD: No financial relationships or conflicts of interest

Case Description: The patient presented with acute onset of a diffuse pruritic rash, bilateral lower extremity edema involving proximal muscle weakness. Dermatology was consulted for the rash and a biopsy was obtained revealing spongiosis and inflammation, without evidence of dermatomyositis. The rash was treated as eczematous dermatitis with triamcinolone and hydroxyzine for pruritis with some improvement. Her lower extremity edema improved with intravenous furosemide, and later transitioned to oral diuretics. Labs revealed an elevated erythrocyte sedimentation rate, c-reactive protein, lactic acid dehydrogenase, and creatine phosphokinase. Upon Rheumatology consult, initial concern for dermatomyositis resulted in intravenous steroid therapy with slow improvement in proximal muscle weakness. Electromyography revealed evidence of myopathy in both the left upper and lower extremity proximal muscles, and a chronic L4-S1 polyradiculopathy. Muscle biopsy obtained from the left thigh showed lobulated muscle fibers, type 2 fiber atrophy, without inflammation or vasculitis to suggest dermatomyositis.

Setting: Tertiary care hospital

Patient: A 67-year-old female with past medical history of idiopathic pulmonary fibrosis, arthritis, and fibromyalgia Assessment/

Results: Patient was later transitioned to oral steroids and admitted to inpatient rehabilitation for intense therapy. Both strength and symptoms improved. Myositis panel revealed positive findings of anti-PL-12 antibody, diagnostic for anti-synthetase syndrome. Rheumatology follow up was recommended upon discharge for disease modifying agent therapy.

Discussion: Anti-synthetase syndrome is relatively acute in disease onset with constitutional symptoms, myositis, Raynaud phenomenon, “mechanic’s hands”, nonerosive arthritis, and interstitial lung disease. Anti-PL-12 antibody is associated with a phenotype of ASS characterized by both severe refractory myositis and ILD.

Conclusion: Differentiation between anti-synthetase syndrome versus dermatomyositis is important due to different therapies. Corticosteroids are commonly used in both, however those with ASS may have corticosteroid-resistant myositis and ILD requiring immunosuppressive therapy. Furthermore, patients with dermatomyositis should routinely undergo anti-PL12 antibody search as this autoantibody impacts patients’ prognosis.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/proximal-muscle-weakness-generalized-rash-and-idiopathic-pulmonary-fibrosis-in-an-adult-female-with-anti-synthetase-syndrome-a-case-report/