Dermatomyositis associated with hepatitis B virus-related hepatocellular carcinoma

Dermatomyositis is an idiopathic inflammatory myopathy with typical cutaneous manifestations. It has been proposed that dermatomyositis may be caused by autoimmune responses to viral infections. Previous studies have shown an association between dermatomyositis and malignant tumors such as ovarian cancer, lung cancer, and colorectal cancer. However, a chronic hepatitis B virus (HBV) infection associated with dermatomyositis and hepatocellular carcinoma (HCC) has been very rarely reported. Here, we report a rare case of dermatomyositis coinciding with HBV-associated HCC. A 55-year-old male was confirmed to have HCC and dermatomyositis based on proximal muscle weakness, typical skin manifestations, elevated muscle enzyme levels, and muscle biopsy findings. This case suggests that HCC and/or a chronic HBV infection may be factors in the pathogenesis of dermatomyositis through a paraneoplastic mechanism.