Dermatomyositis and malignancy in Tunisia: a multicenter national retrospective study of 20 cases

The aim of our study was to report the epidemiologic, clinical, and biologic profiles of dermatomyositis (DM) associated with malignancy in patients from Tunisia. From January 1982 to January 2000, we collected retrospectively 20 case reports of DM associated with cancer from the different university hospital centers of Tunisia. Initial workup included anamnesis, clinical examination, cancer staging and classification, serum muscle enzymes (creatine phosphokinase, lactate dehydrogenase, aldolase, and transaminases), electromyography, and muscular biopsy. We calculated the median survival and mean value of all the variables. Comparisons of statistical tests were done with the Kruskal-Wallis test.

Among the 130 DM cases of our study, 20 were associated with cancer (15.38%). The mean age of our patients was 49.6 years and the sex ratio (female/male) was equal to 3. Cancers were mainly those of the breast (35%) and nasopharynx (25%). DM followed a paraneoplastic course in 90% of the cases. The profile of seric muscular enzymes showed a significant statistical difference (P =.05) between a group of patients with severe muscular weakness and a group with moderate muscle weakness only for creatine kinase. The median survival was 36.5 months after diagnosis of DM and 48.6 months after that of cancer. The 5-year actuarial survival was 38% as related to cancer and 16% as related to DM. Mortality was 45%, in 90% as a result of cancer.

In our study, nasopharyngeal carcinoma represents the second cancer associated with DM, after breast neoplasm, demonstrating the frequency of these 2 cancers in our country. Despite our reduced number of study samples, our study also suggests a relationship between severe muscle weakness and high seric muscle enzymes.