A case of Epstein–Barr virus-associated natural killer/T-cell lymphoma presenting as dermatomyositis: extranodal relapse after 7 years in remission

Inflammatory myopathies and lymphoma

The inflammatory myopathies comprise a group of immune-mediated muscle diseases. Lymphoma is a term for a variety of lymphatic system malignancies. Autoimmune diseases and lymphoproliferative malignancies share a complex bidirectional relationship. A causal relationship between inflammatory mypathies and lymphoma has not been established. The diagnosis/treatment of inflammatory myopathy usually precedes the detection/diagnosis of lymphoma. Immune system dysregulation presumably underlies the evolution of lymphoma in patients with inflammatory myopathies. Inflammatory activity with chronic B-cell activation and/or antigen stimulation is deemed the major risk factor for lymphoma in patients with autoimmunity. A "paraneoplastic" phenomenon or the effects of immunosuppressive therapy may be alternative immune-based mechanisms. In chronic lymphocytic leukemia immune system disturbance rarely results in non-hematological autoimmune disease, including inflammatory myopathies.

A case of nasal-type NK/T cell lymphoma in a patient with dermatomyositis

The association of malignancy with dermatomyositis is well known, and the frequency is reported to be up to 30%. However, cutaneous lymphoma associated with dermatomyositis has rarely been reported. We experienced a case of nasal-type NK/T-cell lymphoma in a 40-year-old woman with a 2-year history of dermatomyositis. To our knowledge, this is the first report of cutaneous involvement of nasal-type NK/T-cell lymphoma developing in a dermatomyositis patient. When skin lesions are resistant to aggressive conventional treatment in dermatomyositis patients, we should consider the possibility of malignancy, especially cutaneous lymphoma.