Presentations

Abstract

Introduction: Anti-synthetase syndrome is a rare idiopathic inflammatory myopathy (IIM) that is characterized by antibodies directed against aminoacyl-transfer RNA (tRNA) synthetases. Currently, there are 10 known such antibodies, with the anti-isoleucyl tRNA synthetase (anti-OJ) antibody having a prevalence of 2-5%. We describe a unique patient presentation who was found to have anti-OJ positive anti-synthetase syndrome after hospitalization for suspected cellulitis.

Case Information: A 38 year-old male with a medical problem list of COPD, asthma, Crohn's disease, rheumatoid arthritis, and ankylosing spondylitis was admitted for abrupt sharp pain in left groin, knee, and ankle. Upon arrival, he was diaphoretic, febrile at 104.5°F, tachypneic, and tachycardic. He endorsed mild dyspnea with chills, diffuse joint pain, and difficulty with moving hands due to pain. Physical exam revealed facial erythema, bilaterally swollen fingers, mild lower extremity edema, erythema on left ankle, and tenderness to palpation of left inguinal fold, left knee, and left lateral ankle. He also had non-blanching petechial rashes on both shins, which the patient stated had been present for years.

Discussion/Clinical Findings: His initial laboratory results were significant for WBC 13,000, PLT 254,000, CPK 546, ESR 28, LDH 245, and mild transaminitis. The initial concern was for sepsis, although procalcitonin and lactate were within normal limits. The source was attributed to cellulitis of his left leg due to mild swelling, increased erythema, and pain, and CT was significant for mild fat stranding of the left thigh with mild lymphadenopathy. Bilateral lower extremity PVLs were negative for DVT. Dermatology and infectious disease were consulted and the petechial rash was attributed to leukocytoclastic vasculitis secondary to infection. Patient was empirically treated with ceftaroline and doxycycline, but he continued to experience recurrent fever to 101°F so he was switched to linezolid due to concern for Group A Strep. Blood cultures were persistently negative, however. Additional investigation revealed that he had no history of smoking, bringing the diagnosis of COPD into question. Pulmonary function tests from the previous year were found to be within normal limits, including before and after bronchodilator administration. The patient also clarified he did not have rheumatoid arthritis and tested negative for rheumatoid factor and anti-CCP antibodies. Furthermore, despite the diagnosis of ankylosing spondylitis, his treatment was only limited to spine injections and he was negative for HLA-B27, with no evidence of sacroiliitis. The patient also shared that he had Raynaud's phenomenon. The workup was expanded to cover a broad differential for polyarthralgia; a myositis panel was obtained given his elevated CPK, and Dnase B antibody was ordered to rule out Group A Strep. The patient's symptoms improved and he was discharged home on oral ciprofloxacin. Dnase B antibody was negative but the myositis panel was positive for anti-OJ antibody. The positive antibody and history of Raynaud's met criteria for anti-synthetase syndrome. The patient and his primary care provider were notified of the result, as well as recommended rheumatologic follow-up.

Conclusion: The symptoms of anti-synthetase syndrome can manifest in presentations similar to other conditions. There are two major classification criteria proposed for the diagnosis, Connor's and Solomon's criteria, both of which require a positive aminoacyl-transfer RNA (tRNA) synthetase antibody. Criteria can then be fulfilled by at least one of the following: fever unexplained by other causes, interstitial lung disease, "mechanic's hands", arthritis, Raynaud's phenomenon, and inflammatory myopathy by Bohan and Peter criteria. This case intends to raise awareness about the possibility of an inflammatory myopathy or autoimmune etiology in patients with negative infectious cultures, yet have symptoms of polyarthralgia, rash, and shortness of breath. It also emphasizes the importance of finding supporting clinical evidence for a listed medical diagnosis.