Dermatomyositis related to autoimmune thyroiditis

Background and objective Reports on the coexistence of dermatomyositis (DM) with autoimmune thyroiditis (AIT) are very few. Our aim is to define the relationship of the two conditions, identify clinical, laboratory, electromyographic and pathologic features of coexistent DM and AIT. Methods We underwent a MEDLINE search to identify relevant literature published in the past 30 years. Concurrently, we analysed retrospectively medical records of five patients diagnosed with DM and AIT from our hospital. Results Eleven cases were included. 90.9% of patients were female with a mean (SD) age of 44.18 (13.11) years for DM at diagnosis, and 39.00 (7.81) years for AIT. AIT can precede or parallel the diagnosis of DM. The most common comorbidities included hypothyroidism (90.9%), cardiopulmonary diseases (63.7%) and overlap syndrome (27.3%), while only one case had malignancy. The most common clinical manifestations were: muscle weakness (100%), polyarthralgia (45.5%), heliotrope rash (45.5%), myalgia (36.4%), and Raynaud’s phenomenon (27.3%). The abnormalities on electromyography and muscle/skin biopsy of DM related to AIT did not differ from those findings of DM, while none of these reports were normal. All patients received both the treatment of corticosteroids and levothyroxine, and only 27.3% of patients had a good prognosis. Conclusion Prevalence of cancer in coexistent DM and AIT may be very low. Also, it is reasonable to suggest that DM patients with AIT should be routinely evaluated for thyroid function and the emergence of comorbidities. Moreover, corticosteroids combined with levothyroxine may be useful for these patients as a standard treatment.