Rare association of chronic lymphocytic thyroiditis with dermatomyositis

Autoimmune thyroid disease (AITD) has been associated with other autoimmune diseases such as chronic urticaria, insulin-dependent diabetes mellitus, Sjøgren's syndrome, inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, psoriasis, ankylosing spondylitis, and dermatomyositis (DM). AITD is a common disorder affecting primarily women, and both genetic and environmental factors are included in its pathogenesis. DM is considered an autoimmune disease of the muscles and skin. Although AITD is the most common cause of hypothyroidism, to the best of our knowledge, only three cases of DM and AITD in the same patient have been reported in the last 40 years. We consider that both are developed from the same autoimmune background. Herein, we present a case of a 30-year-old man with a 4-year history of AITD who was diagnosed as suffering as well from DM.