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Neurology India, Vol. 59, No. 2, March-April, 2011, pp. 306-307 Letter to Editor Resistant dermatomyositis complicated by tubercular myositis and successfully treated with rituximab Ramesh Jois1, Nikhila Vasudevan2, Pradeep Srinivasan1, Ravindra Mehta3 1 Department of Rheumatology, Fortis Hospital, Bangalore, Karnataka, India Correspondence Address: Ramesh Jois, Department of Rheumatology, Fortis Hospital, Bangalore, Karnataka, India, rammi09@yahoo.com Code Number: ni11087PMID: 21483146 DOI: 10.4103/0028-3886.79163 Sir, B-cell depleting monoclonal antibody rituximab (RTX) has been shown to be effective in patients with refractory dermatomyositis (DM). [1],[2],[3],[4] Biological therapy is associated with an increased risk of tuberculosis (TB); however, this risk is negligible with RTX. [5] We report an unusual patient of drug refractory DM complicated by tuberculous myositis and successful treatment with RTX. A 35-year-old lady presented with severe myalgia, proximal muscle weakness, and skin rash. She was diagnosed as a case of DM based on elevated creatinine phosphokinase (CK; 13,119 U/L), electromyography features being suggestive of primary muscle disease, and muscle biopsy consistent with DM. The work-up for underlying malignancy was negative. She was initially started on prednisolone and azathioprine. Her weakness worsened over the next 2 months, although CK was normalized. Azathioprine was substituted by methotrexate but had to be discontinued as she developed anaphylaxis. She was then initiated on mycophenolate mofetil (MMF). A month later, she presented with fever, heliotrope rash, worsening of muscle weakness, and severe thigh and gluteal tenderness. Repeat CK was normal. Investigations for underlying infection were negative. Despite a course of intravenous immunoglobulin (IVIg), her myalgia worsened. She developed boggy lumps in the lower third of the left thigh and gluteal region. Magnetic resonance imaging (MRI) of the left leg revealed acute myositis and subcutaneous fluid collection in the areas mentioned [Figure - 1]. The fluid from the lump showed plenty of acid-fast bacilli. A diagnosis of tuberculous myositis and abscess was considered. Mycobacterium tuberculosis was subsequently isolated from the pus culture. MMF was discontinued and prednisolone was reduced to 15 mg/day. Antituberculous therapy (ATT) resulted in a complete resolution of the abscess and muscle pains. Four months later, she had worsening of neck and limb weakness and elevation of CK, 865 U/L. An increase in the steroid dose and MMF led to the recurrence of the muscle abscess. She was given another course of IVIg with which the neck weakness improved but not limb weakness and CK increased to 4930 U/L. She was given two doses of RTX, 1 g each, 2 weeks apart while continuing ATT. She showed gradual improvement in the muscle weakness and also a progressive decline in CK values. At 4 months of the last dose of RTX, CK was 246 U/L and muscle power was normal. Seven months later, she was independent in her daily activities, and ATT was stopped, prednisolone was reduced to 7.5 mg while MMF is being continued. She has been in remission for 24 months. At the last follow-up, she was on prednisolone 2.5 mg and MMF. The co-occurrence of TB myositis with DM is extremely rare [6],[7] and must be considered as a possible cause of myositis in immunosuppressed patients, especially in high endemic areas. Treatment options for DM in this setting are limited. A significant disturbance of B-cell function is seen in DM. B-cell driven response with clonal expansion, isotype switch ultimately causing altered plasma cell maturation has been observed. [8] The B-cell functions in DM form the rationale to specifically target B-cell with RTX. An open-label study and few case reports have shown significant improvement with RTX therapy in refractory DM. [1],[2],[3],[4] A recent review of all published cases of DM treated with RTX noted a response rate of 71.4%. [1] The median time free of symptoms between two courses of RTX was 12 months. Maximal improvement in muscle strength was seen by 12 weeks. [2] Four of the six patients experienced recurrence, which improved after a second course of RTX. The average prednisolone dosage could be decreased (from 16.7 to 4 mg) and MTX could be reduced by 50%. [3] Remarkable improvements in muscle weakness and CK in our patient with RTX therapy were consistent with findings from the earlier reports. Our patient is probably the first published case of use of RTX in the setting of refractory DM and tuberculous myositis. References
Copyright 2011 - Neurology India The following images related to this document are available:Photo images[ni11087f1.jpg] |
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