en Dermathology Dermathology Review Article Review Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background</span></i></b><i><span style="color:blue">:</span></i> <span style="color:black">Cutaneous Rosai-Dorfman disease (CRDD) is a rare variant of benign histiocytic proliferative disorder limited to the skin. The underlying etiology is still unclear, but it had been claimed that infections, immunodeficiencies, and autoimmune disorders might have a role in the etiology of this disorder. The characteristic presentation of RDD is lymphadenopathy due to abnormal production and accumulation of histiocytes in lymph nodes; however, the extra-nodal areas could also be affected, such as cutaneous. Herein, we presented a 45-year-old Iranian woman presented with an atypical pure cutaneous Rosai Dorfman disease, in addition to a summarized list of atypical cases of RDD that are reported as pure cutaneous RDD with atypical presentation.</span><span style="font-size:9.0pt"></span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Case presentation</span></i></b><i><span style="color:blue">:</span></i><span style="color:black">&nbsp; Herein, we presented a 45-year-old woman who referred to us with an ulcerative nodule with a size of 5&times;5 cm on her buttock, gradually growing over one year. After the primary evaluations, a biopsy specimen was obtained, and histologic studies revealed a dense cellular infiltrate involving the dermis and the subcutis, which was composed of abundant sheets of large histiocytes with admixtures of lymphocytes, plasma cells, neutrophils, and eosinophils within their cytoplasm -known as the emperipolesis phenomenon. The immunohistochemistry staining was positive for S100 and CD68 and negative for CD1a.</span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion:</span></i></b><span style="color:black"> The diagnosis of CRDD was confirmed based on these histopathological findings.</span><b><i><span style="color:blue"></span></i></b></span></span></span><br> &nbsp; pure cutaneous Rosai Dorfman disease,histiocytosis, atypical cutaneous presentation,non-Langerhans cell histiocytosis, review, case report, histopathology 818 826 http://caspjim.com/browse.php?a_code=A-10-170-7&slc_lang=en&sid=1 Fatemeh Montazer montazer.f@iums.ac.ir 100319475328460039926 100319475328460039926 No Department of pathology, Iran University of Medical Sciences, Tehran, Iran Saeedeh Farahani Farahani.104@gmail.com 100319475328460039927 100319475328460039927 No Department of Dermatology, RasoolAkram Medical Complex, Iran University of Medical Sciences, Tehran, Iran Zoha Shaka Zohashaka@gmail.com 100319475328460039928 100319475328460039928 No School of Medicine, Iran University of Medical Sciences, Tehran, Iran Zeinab Aryanian aryanian@sina.tums.ac.ir 100319475328460039929 100319475328460039929 No Autoimmune Bullous Diseases Research Center, Tehran University of Medical Sciences, Tehran, Iran Azadeh Goodarzi azadeh_goodarzi1984@yahoo.com 100319475328460039930 100319475328460039930 Yes Department of Dermatology, Rasool Akram Medical Complex, Iran University of Medical Sciences, Tehran, Iran