Dermatomyositis associated with lymphoproliferative disorder of NK cells and occult small cell lung carcinoma.

We report a case of dermatomyositis that was associated with a marked expansion of circulating NK cells (CD3-CD16+) with homogeneous phenotype (CD56- CD94- CD159a- CD244+) which satisfied the updated diagnostic criteria for the lymphoproliferative disorder of granular lymphocytes/NK cells. Immunosuppressive treatment induced remission of the dermatomyositis and decreased the number of circulating NK cells. However, a small cell lung carcinoma, that was occult at the time of the presentation of dermatomyositis, was diagnosed 10 months thereafter.