A case of dermatomyositis associated with prostatic carcinoma: a case report

We report a case of dermatomyositis associated with prostatic carcinoma. A 69-year-old male was admitted to the Department of Internal Medicine with the chief complaint of general fatigue, appetite loss and facial anthema. Abdominal ultrasound demonstrated swollen periaortic lymph nodes and the margin of prostate was unclear. Prostatic carcinoma was suspected based on digital rectal examination, so he was admitted to our department. Serum prostate specific antigen level was 190 ng/ml. He was examined by a dermatologist because of deterioration of anthema. Dermatomyocitis was demonstrated by dermatoses (edema erythema at face, neck and limbs, nail fold thrombosis and poikiloderma), high serum level of creatine phosphokinase and a decrease in muscular strength (especially at the proximal musculus). There was no interstitial pneumonitis or malignancy of the digestive system. On needle biopsy of the prostate and quadriceps femoris muscle, prostatic carcinoma (poorly differentiated adenocarcinoma, Gleason score 5 + 5) and myositis were suspected. The stage of prostatic carcinoma was T4N1M1. The patient was treated by administration of diethylstilbestrol phosphate and prednisolone for prostatic carcinoma and dermatomyositis, respectively, but he died of multiple metastasis of the tumor 1 year and 5 months later. Dermatomyocitis is associated with malignancy more frequently than any other collagen disease. In Japan, it is frequently complicated by gastric, lung and mammory cancers, but rarely by prostatic carcinoma. To our knowledge, this is the fourth case of prostatic carcinoma associated with dermatomyocitis in Japan.