I was diagnosed with Hashimoto's hypothyroidism in May 2015 and began levothyroxine treatment. About the same time I developed muscle weakness, skin rashes and began to lose weight. These symptoms accelerated during the autumn and in December I was diagnosed with dermatomysositis. Fortunately no malignancy has been found so far and both conditions are responding to treatment. I should be interested to hear from anyone with experience of dermatomyositis associated with Hashimoto's hypothyroidism and what the longer term prognosis may be. I am 69 and male.