Disclosures: Alex Vertes, MD, MPH: No financial relationships or conflicts of interest

Case Diagnosis: 40-year-old female with mixed connective tissue disease (MCTD)

Case Description or Program Description: Patient presented with 5 months of proximal upper and lower extremity muscle weakness and pain along with difficulty swallowing, fatigue and unintentional weight loss. Physical exam revealed diminished proximal upper and lower extremity muscle strength, shoulder wasting, and swelling of the hands and feet. Laboratory workup showed elevated CPK, ESR, and LDH. Rheumatologic panels were positive for ANA, anti-ds-DNA, anti-SM antibody, anti-nRNP, anti-RNA II, and RF. MRI of lower extremities showed diffuse inflammatory changes of musculature with proteinaceous exudate indicative of rhabdomyolysis. Workup was consistent with MCTD with features of lupus myositis.

Setting: Tertiary Care Academic Hospital

Assessment/Results: Patient treated with methylprednisolone for 3 days and IVIG for 2 days with limited response so mycophenolate mofetil and hydroxychloroquine were started. However due to persistently high CPK, patient was progressively treated with prednisone, therapeutic plasmapharesis for 5 days, 2 infusions of rituximab, and finally addition of tacrolimus. Following a course of acute rehabilitation and 1 month after initial presentation, proximal muscle weakness and dysphagia gradually improved to near baseline and CPK trended down to normal range.

Discussion (relevance): MCTD is an autoimmune general connective tissue disorder with features of systemic lupus erythematosus, polymyositis, systemic sclerosis, edematous hands, severe arthritis, and insidious pulmonary hypertension. Standard care of treatment includes corticosteroids as well as targeted therapy for specific symptoms. However, there are cases of resistant MCTD requiring stronger treatment like high dose corticosteroids and methotrexate. Our case of MCTD presented with unusually severe myositis, was refractory to corticosteroids, and required multiple treatment modalities.

Conclusions: We highlight an atypical case of MCTD with severe myositis and muscle weakness refractory to multiple treatments. Considering the rare presentation of myositis with MCTD, prompt diagnosis and treatment is crucial for a favorable patient prognosis.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/treatment-refractory-mixed-connective-tissue-disease-with-myositis-a-case-report/