Polymyositis and dermatomyositis in Sarawak: a profile of patients treated in the Sarawak General Hospital

We performed a cross-sectional study of the demography, clinical and laboratory features of patients with polymyositis and dermatomyositis followed up in our centre from 2006 to 2009. There were 12 cases, with the majority of them (58.3%) being woman. They have a mean age of 57.8 years and mean disease duration of 11.83 (SD 9.92) months. Our patients comprised of multi-ethnic groups with predominantly Chinese (83.3%), Sarawak natives (8.3%) and Malays (8.3%). They have a mean lag time to diagnosis of 3.67 (SD 4.27) months. Nine (75%) patients had dermatomyositis and 3(25%) had polymyositis. The common clinical manifestations found in our patients were proximal myopathy (100%), neck weakness (33.3%), dysphagia (33.3%) and interstitial lung disease (33.3%). For the nine patients with dermatomyositis, the most common dermatological manifestations were shawl sign (88.9%) and V sign (88.9%). Muscle enzymes were raised in 91.7% of patients. Electromyographies were carried out in four patients, and only one of our patients had muscle biopsy. Only 41.7% of our patients have positive ANA. The majority received prednisolone (100%) and hydroxychloroquine (58.3%). Malignancy occurred in five (three nasopharyngeal carcinomas, one sigmoid colon cancer and one lung cancer) out of the nine dermatomyositis patients but none in the polymyositis group. The mortality rate in our group was 4(33.3%) over the 4-year period. This study demonstrated the rarity of PM/DM in our centre with considerable lag time to diagnosis in our patients. Despite lack of muscle biopsy in our centre, our centre achieved appropriate diagnosis and management of PM/DM.