Related Experiment Videos
[135 cases of polymyositis]
Abstract:
The classification of 135 patients with either dermatomyositis (DM) or polymyositis (PM) showed 34 cases of DM and 56 cases of PM in adults, 6 cases of DM associated with cancer, 9 cases of DM in children, 16 cases of localized PM and 14 cases of an overlapping syndrome. Results of biological tests, erythrocyte sedimentation rate and serum enzyme determinations were inconstantly abnormal. The electromyograms were generally of a myogenic type with spontaneous activity in about half the cases. Muscle biopsy usually showed inflammation necrosis and regeneration, sometimes only of moderate severity only. Results were normal in several cases. In 21 patients only the pathognomonic perifascicular atrophy was reported. Proposed classifications are unsatisfactory. Polymyositis may be considered as a syndrome. Among the primary forms the distinction between acute dermatomyositis and subacute or chronic polymyositis is poorly defined and passage from one disorder to another is frequent. Pseudo-myasthenic forms are not entities and pseudo-myopathic types are actually muscular dystrophies. Associations with polymyositis are common and may consist only in the addition of one sign of no clinical significance (PM "plus"). The polymyositis lesion may be part of a syndrome such as Gougerot-Sjögren's or of another connective tissue disease. A system of diagnostic criteria uses numerical ratings of each criterion as a function of its semiologic importance.
Insights
Classifying dermatomyositis and polymyositis is challenging, with current diagnostic criteria being unsatisfactory. Further research is needed to refine diagnostic approaches for these inflammatory myopathies.
Area of Science:
- Neurology
- Rheumatology
- Immunology
Context:
- The classification of inflammatory myopathies, specifically dermatomyositis (DM) and polymyositis (PM), presents diagnostic challenges.
- A study analyzed 135 patients diagnosed with DM or PM, examining clinical presentations, diagnostic test results, and pathological findings.
Purpose:
- To evaluate the effectiveness of current classification systems for dermatomyositis and polymyositis.
- To identify limitations in distinguishing between DM and PM and their subtypes.
- To explore the diagnostic utility of various tests and pathological markers.
Summary:
- The study reviewed 135 cases of DM and PM, noting the distribution of subtypes including adult DM/PM, cancer-associated DM, juvenile DM, localized PM, and overlapping syndromes.
- Biological tests (ESR, serum enzymes) showed inconsistent abnormalities. Electromyography (EMG) typically indicated myogenic changes with spontaneous activity in half the cases.
- Muscle biopsy findings varied, with inflammation, necrosis, and regeneration observed, but perifascicular atrophy was only reported in 21 patients. Normal biopsies occurred in some cases.
- Current classification systems were deemed unsatisfactory, highlighting the poorly defined distinctions between acute DM and subacute/chronic PM, and the frequent overlap between these conditions.
- The study suggests polymyositis may be a syndrome, and pseudo-myasthenic/myopathic forms are not distinct entities. Associations with other connective tissue diseases are common.
Impact:
- Highlights the need for improved diagnostic criteria for DM and PM to enhance clinical management and research.
- Suggests a re-evaluation of polymyositis as a distinct entity versus a syndrome.
- Underscores the variability in diagnostic test results and biopsy findings, emphasizing the complexity of these autoimmune diseases.