Dermatomyositis and polymyositis associated with malignancy: a 21-year retrospective study

Area of Science:

• Rheumatology
• Oncology
• Clinical Immunology

Background:

• Myositis, including dermatomyositis and polymyositis, is a rare idiopathic inflammatory myopathy.
• Association between myositis and malignancy is a known but complex phenomenon requiring further investigation.
• Understanding this association is crucial for timely diagnosis and improved patient outcomes.

Purpose of the Study:

• To retrospectively analyze clinical and laboratory data of patients diagnosed with dermato- or polymyositis.
• To investigate the association between myositis and malignant diseases.
• To evaluate immunological features, therapeutic responses, and survival data in relation to malignancy.

Main Methods:

• Retrospective analysis of 309 myositis patients diagnosed between 1985 and 2006.
• Clinical assessment, immunological profiling, and survival data analysis.
• Investigation of HLA haplotypes in 155 myositis patients.

Main Results:

• Malignant disease was identified in 37 (12%) of the 309 myositis patients.
• In 64.8% of cases, malignancy and myositis appeared within one year of each other.
• Breast cancer and adenocarcinoma were the most frequent malignancies; skin and diaphragmatic involvement were severe, with lower enzyme elevations compared to primary myositis.

Conclusions:

• Tumor-associated myositis often requires additional immunosuppressive drugs beyond glucocorticoids.
• Successful treatment of the underlying malignancy led to clinical improvement in myositis.
• Overall survival rates for patients with tumor-associated myositis were significantly worse than for other myositis forms.