2022 Volume 21 Issue 1 Pages 46-52
We report a case of Rosai-Dorfman disease (RDD). A 62-year-old Japanese male noticed a subcutaneous mass on the neck six months prior to his first visit. He was examined byhis family doctor because of subcutaneous masses on the chest and back. The familydoctor took a skin excision, which revealed large foamy histiocytes in the dermis. Large histiocytes were diffusely infiltrated and emperiporesis, in which morphologicallypreserved leukocytes are trapped in the cytoplasm of histiocytes, was observed. The patient was referred to our department for suspicion of RDD. On his first visit to our department, two subcutaneous masses on the right upper arm were excised under local anesthesia for diagnostic purposes. Histopathological examination revealed similar histological findings as those of his previous doctor. From the deep dermis to the fat tissue,S-100 and CD68 stain showed positive, and CD1a stain showed negative histiocytes. The results of these immunohistochemical tests were consistent with RDD. The diagnosis was confirmed. The patient is currentlybeing followed up every3 months, and has passed 2 years without organ compression or airwayinvolvement. In the cases reported between 2014 and 2019 in Japan, about half of the cases were in women aged 45 years or older and skin lesion was found in 20%, followed by the neck lesion in 15%. In the U.S.A., RDD is often reported to occur at a young age ; however, in Japan, there are manyreports of elderlypatients with RDD ; thus, there maybe racial or regional differences. This present patient is a rare case of systemic RDD in Japan. Skin Research, 21 : 46-52, 2022
