Inflammatory myopathies--a review of newly diagnosed patients (2004-2008) in the Counties Manukau region.

Aims: To estimate incidence, review clinical characteristics and management of newly diagnosed patients with idiopathic inflammatory myositis in Counties Manukau and to compare the findings with other reported series in New Zealand and overseas.

Methods: A case note study of computer generated data of patients having a diagnosis of inflammatory myopathy from January 2004 to December 2008 were included in this retrospective review.

Results: Twelve patients were newly diagnosed in the 5-year period. Polymyositis (PM) was diagnosed in 58%, dermatomyositis (DM) in 33% and inclusion body myositis (IBM) in 8%. Amyopathic dermatomyositis (ADM) and malignancy associated dermatomyositis were diagnosed in one patient each. There was slight preponderance of men in dermatomyositis and women in polymyositis. Muscle biopsy was performed in 75% and electromyography was reported in 58%. High-dose prednisone was administered to 83%, and 50 % required other immunosuppressives, such as methotrexate (33%) and azathioprine (16%). Overall therapeutic response was good (75%) with 2 deaths (17%), one each in dermatomyositis and polymyositis. Regular follow-up was maintained in 92 %. Nasopharyngeal carcinoma was diagnosed in a patient with polymositis during follow up.

Conclusions: Idiopathic inflammatory myositis is a challenging group of heterogenous disorders. This study highlights the need to review current criteria to include subcategories, such as amyopathic dermatomyositis, and the importance of long term surveillance to detect occult malignancy.