rosai - dorfman disease is an uncommon histiocytic proliferative disorder , which can manifest solely in the skin . rosai - dorfman disease ( rdd ) , also known as sinus histiocytosis with massive lymphadenopathy , is a benign multi - organ non - langerhans cell histiocytic proliferation that was first described in 1969 by rosai and dorfman . the disease most commonly involves the lymph nodes but can be seen in virtually any part of the body ; the presentation is usually painless massive bilateral cervical lymphadenopathy . skin lesions occur in a minority of patients with systemic disease ; nonetheless the cutaneous form of rdd , also known as cutaneous sinus histiocytosis , is a rarer entity and is detectable in only 3% of reported cases . the etiology of rdd is unknown , as are the cases with the purely cutaneous form . in some patients , there have been implications of infectious agents including epstein - barr virus , human herpesvirus six , parvovirus b19 , herpes simplex virus , brucella , klebsiella rhinoscleromatis and nocardia based on positive serology and temporal association . an immunologic reaction triggered by various agents ( rather than a single immunologic , infectious , or neoplastic process ) has also been proposed . patients with cutaneous rdd usually present with a painless mass without lymphadenopathy or systemic symptoms , such as elevated white blood cell count with neutrophilia , fever , erythrocyte sedimentation rate , and/or hypergammaglobulinemia that can be seen in the usual presentation of rdd . though , one study on 21 lesions states that the skin - limited form shows no specific predilection for a particular location of the body , another more recent study on 25 patients found that the extremities were the most frequently involved site . characteristic demographics of patients with the cutaneous version of rdd include an older age of onset , female predominance , and a predilection for patients of asian and white extraction . a 65-year - old white male presented with a singular , 0.8 cm , and slowly growing mass on the right back for evaluation . grossly , the lesion was a firm , dome - shaped nodule that was brownish - red in color . the patient reported no associated systemic symptoms , such as fever , weight loss , or malaise . past medical history of this patient , includes hypertension , steatosis , and over 20 subcutaneous nodules scattered over the forearms , trunk , and neck , which have been surgically excised and diagnosed as lipomas after histopathologic examination . previous radiologic studies with magnetic resonance imaging demonstrated multiple solitary mobile subcutaneous nodules of fatty tissue measuring a few centimeters in diameter . all pertinent laboratory results including complete blood count with differential and erythrocyte sedimentation rate were unremarkable . histologic evaluation shows the dermis occupied by a sheet of confluent histiocytes with scattered neutrophils , lymphocytes , and plasma cells interspersed [ figure 1 ] . the histiocytes have indistinct cell borders , abundant eosinophilic cytoplasm , low nuclear to cytoplasmic ratio , round vesicular nuclei , and prominent nucleoli . within some of the histiocytes were intact lymphocytes , plasma cells , and neutrophils that were engulfed by the histiocytes , a process called emperipolesis [ figure 2 ] . the histiocytes are positive for s-100 [ figure 3 ] and cd ( cluster of differentiation ) 68 [ figure 4 ] , and negative for cd1a . the lesion was completely resected and follow - up reveals no recurrence or new nodules , and no signs of systemic involvement . h and e of diffuse histiocytic infiltrate in the dermis , 100 h and e of histiocytes engulfing other inflammatory cells ( emperipolesis ) , 400 s-100 stain , positive in the histiocytes , 400 cd68 stain , positive in the histiocytes , 400 classic cutaneous rdd presents as firm red to red - brown or xanthomatous macules , papules , nodules or plaques with satellite lesions that are slow growing and frequently multifocal and clustered . the skin lesions may be variable in size from 1 cm to 30 cm and appear clinically non - specific . on dermoscopy , lesions classically resemble ovoid structures on an erythematous base with multiple yellowish structures in the periphery . the soft - tissues remain among the most common extra - nodal sites of involvement for rdd . given the fact that the clinical lesions of rdd are relatively non - specific , other histiocytoses , infectious processes , sarcoidosis , and infiltrative disorders should also be considered as part of the differential diagnosis . the diagnosis of cutaneous rdd is differentiated from other histiocytic conditions such as areticulohistiocytoma and xanthogranuloma by the combination of clinical findings accompanied by histopathologic and immunohistochemical confirmation . although , emperipolesis has been recently described in h syndrome , the clinical findings and age of presentation is not consistent with our case . the key characteristics of this genodermatosis such as hypertrichosis , hyperpigmentation , and indurated patches of skin along with frequent multi - organ associations including hearing loss , hypogonadism , hepatosplenomegaly , short stature , cardiac anomalies , and scrotal masses are not present in our patient thus making it an unlikely diagnosis . additionally , biopsies of involved skin in h syndrome demonstrate acanthosis and the infiltrate is composed of mast cells as well as histiocytes and plasma cells . the immunohistochemical profile for this lesion though in many cases , the cutaneous histopathology may be very non - specific , and the diagnosis may not be clear until there is evaluation of lymph node or other organ involvement , which places the patient at risk for serious complications . this disease is considered self - limited due to spontaneous resolution and usually does not require aggressive intervention unless bothersome to the patient or leads to significant functional or physical impairment , such as compression of a vital organ . yet there are numerous treatment modalities for cutaneous rdd , including surgical excision , corticosteroids , thalidomide , cryosurgery , radiotherapy , dapsone , isotretinoin , interferon  , acitretin , and pulsed dye laser ; all of these agents have shown varying rates of success . in a clinical and histopathologic study of 25 patients with cutaneous rdd , clinical follow - up in 22 patients indicated that surgical excision was the exclusive effective treatment . due to the rarity of the disorder , our patient 's nodule was completely excised indicating that surgical excision is an effective option for management . diagnosis is made by histopathologic examination , where microscopy shows a diffuse infiltrate of typically large , polygonal histiocytes with abundant palely eosinophilic cytoplasm and engulfment of other inflammatory cells . the presence of emperipolesis as observed in this case serves as a very important diagnostic feature and can be highlighted by the s-100 protein stain . the presence of consistent histopathologic and immunohistochemical findings in skin lesions permit diagnosis even in cases without lymph node involvement .
background : the cutaneous form of rosai - dorfman disease ( rdd ) is a rare entity that manifests solely with skin papules or nodules and does not present with the usual myriad of symptoms of classical rdd.aims:to analyze the most recent publications regarding cutaneous rdd to point out updated , relevant aspects regarding future directions for clinical recognition and management . to identify histopathologic and immunohistochemical findings in skin lesions that permit diagnosis.materials and methods : we present a case of a gentleman with a history of multiple lipomas with a new solitary nodule on physical exam ; microscopic examination shows the typical findings of rdd with the associated diagnostic immunohistochemical profile , as well as the expected finding of histiocytes engulfing other intact inflammatory cells.results:our patient was managed with surgical excision of the entire lesion , one of the several available treatment options . 
 long - term follow - up 2 years later did not reveal any complications , recurrences , or new lesions.conclusion:the diagnosis of cutaneous rdd is differentiated from other histiocytic conditions by the combination of clinical findings accompanied by histopathologic and immunohistochemical confirmation .