LAUSR

A 45-year-old woman presented to our institution with progressive upper and lower extremity proximal weakness of a few weeks’ duration. Three months prior, the patient received a diagnosis of systemic lupus erythematosus and started on hydroxychloroquine; she had been treated with low-dose prednisone for her weakness for the last three weeks. Physical examination showed severe proximal weakness, grade 2/5, in the bilateral upper and lower extremities with retained strength in all other muscle groups. The patient had an erythematous rash on her face, chest and upper back. There was no clinical evidence of involvement of other organs. Serum creatinine kinase (CK) was >50 000 U/L. CT scan of the chest/abdomen/pelvis revealed no evidence of malignancy or interstitial lung disease (ILD). Serology was positive for ANA, but with negative ENA and dsDNA. She tested positive for anti-PL-7 and anti-Mi2. The rest of the myositis-specific and-associated antibodies were negative including anti-TIF1γ, anti-MDA-5, antiNXP2, anti-SAE1, anti-Jo-1, anti-PL-12, anti-EJ and anti-OJ. The patient underwent a muscle biopsy of the left vastus lateralis. Prednisone was continued together with methotrexate and intravenous immunoglobulin was added. At follow-up one month later, she showed clinical improvement of proximal muscle strength (4to 4/5 bilateral upper and lower extremities) and CK decreased to 1169 U/L.