Dr. Ashwin Kulkarni M.S.Ramaiah Medicial College Bangalore India Importance of follow up in the diagnosis of Overlap Myositis – A review article Dr. Ashwin Kulkarni M.S.Ramaiah Medicial College Bangalore India

INTRODUCTION- Overlap myositis is an idiopathic inflammatory myopathy characterized by myositis with at least one clinical and/or autoantibody overlap feature with connective tissue disorder. Diagnosis requires high index of suspicion. Clinical features may be subtle at presentation where in continuous follow up helps in the diagnosis of overlap myositis. Here we present three cases of overlap myositis diagnosed during follow up.

CASE-1 A 49 year old male patient presented with history of thickening and tightening of skin around his fingers, hand, upper limb, chest and face since 1 year. He also gave history of difficulty in swallowing and regurgitation since 5 months. Routine investigations were normal Anti Nuclear Antibody - Positive ++ (nucleolar pattern) Anti Centromere, Anti-topoisomerase antibodies were negative

Skin biopsy - Dermis shows thick homogenous collagen bundles and perivascular and periadnexal lymphoplasmacytic cells (features consistent with systemic sclerosis). Based on the 2015 scoring system by American College of Rheumatology criteria for the classification of systemic sclerosis, this patient has a score of 11 (score above 9 is diagnostic of systemic sclerosis).

After 3 months, he started developing weakness of neck muscles After 3 months, he started developing weakness of neck muscles. He has difficulty holding his head up right. He also had weakness of all 4 limbs. Creatitine Kinase -1500 U/L Muscle biopsy - showed peri fasical atrophy and diffuse infiltration of muscle fibres with perivascular infiltrates consistent with dermatomyositis EMG- features suggestive of myopathic pattern

CASE-2 A 45yrs old female presented to hospital with chief complaint of fever 2 months back and diffuse thickening and reddness of her skin. ANA-IF : 4+ positive( speckled pattern) ANA profile : positive for Scl-70, PM-Scl. After 1 month patient developed muscle pain and weakness of all limbs manifested as difficulty in combing hair, carrying food to mouth, climbing stairs and later progressed to involve distal muscles.

Creatinine phosphokinase : 7973U/L. Serum Anti-Jo antibodies was positive. Electromyogram: Myopathic pattern of weakness Muscle biopsy: there were areas of necrosis, regeneration and inflammatory cells infiltrated around muscle fibres predominantly CD8+ t lymphocytes suggesting inflammatory myopathy. In this case muscle weakness was not present at the time of presentation but developed later and diagnosed during follow up.

CASE-3 A 40 yrs old female presented to hospital with complaint of fever since 1 month. On examination she had malar rash, diffuse aloepecia and multiple cervical lymphadenopathy. Biopsy of lymphnode was suggestive of Kikuchi Disease. ANA – IF : POSITIVE. Anti ds DNA anitbodies positive. She was diagnosed to have SLE based on ACR Criteria. .

1 month later the patient presented with myalgias and weakness of all 4 limbs. On examination she had symmetric proximal muscle weakness. Serum CPK levels were 2500 and EMG showed Myopathic pattern of weakness. A diagnosis of inflammatory myopathy was made based on Bohans and Peters criteria and Overlap myositis because of associated SLE.

DISCUSSION Overlap myositis is an Inflammatory myositis with clinical overlap with other connective tissue disease or an overlapping antibody. Muscle weakness may be a late presentation. Regular follow up helps to identify muscle involvement. Detailed musculoskeletal and neurological examination should be done with serum CPK , Electromyogram, Overlap antibody testing and muscle biopsy when necessary

CONCLUSION Regular follow up with specific clinical and lab testing is necessary for diagnosis of overlap myositis.

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