Paraneoplastic dermatomyositis and prostate cancer: Myopathy regression under cancer-directed therapy.

Prostate cancer is the second most frequent malignancy in men worldwide and the fifth leading cause of death. Dermatomyositis (DM) is a rare idiopathic inflammatory myopathy characterized by musculocutaneous manifestations. However, DM can also present as a paraneoplastic syndrome of an underlying neoplasm. We report a case of a 65-year-old man diagnosed with prostate adenocarcinoma in the setting of severe dysphagia, muscle weakness and a facial erythematous rash. At first, the DM-related symptoms resolved with the initial treatment for the underlying malignancy. Yet, they flared up as the tumor progressed. To sum up, DM is a rare systemic disorder with unknown etiology. There is a well-established association between DM and malignancy. Malignancy-headed therapy can improve DM manifestations and the recurrence of DM symptoms may act as an early warning of malignancy relapse.