sinus histiocytosis with massive lymphadenopathy ( shml ) , is a benign , self - limiting disorder that commonly involves the lymph nodes . first described by rosai and dorfman in 1969 , many more cases have been added to the literature but the cytomorphology has been documented in relatively few cases . it is characterised by painless , bilateral , cervical lymphadenopathy accompanied by fever , leukocytosis , elevated erythrocyte sedimentation rate ( esr ) , and hypergammaglobulinemia . other lymph nodes as well as extranodal sites such as the eyes and ocular adnexa , head and neck , upper respiratory tract , skin , subcutaneous tissue , bone , skeletal muscle , central nervous system , gastrointestinal tract , salivary glands , genitourinary tract , thyroid , breast , liver , kidney , heart , uterine cervix , etc . , may also be involved . whereas patients presenting with lymphadenopathy are commonly diagnosed as having malignant lymphomas , cases with extranodal involvement are suspected of having various neoplasms , depending on the site of involvement . cytological features of shml are virtually diagnostic and can obviate the need for a biopsy in most cases . a 23 year - old male presented in the fine needle aspiration cytology ( fnac ) clinic with multiple , bilateral , soft to firm , nontender , upper , deep cervical and submandibular lymphadenopathy of eight months duration , accompanied by low - grade fever . the lymph nodes had been gradually increasing in size and number during this period ; there was no history of weight loss . clinical examination showed multiple , enlarged , bilateral , cervical and submandibular lymph nodes , ranging in size from 1  1 cm to 3  3 cm . esr was 40 mm at the end of one hour and the serum gammaglobulins were raised . ultrasonography of the abdomen did not reveal any organomegaly ; the patient was clinically diagnosed as having hodgkin 's lymphoma . low - power microscopic examination revealed the presence of diffusely distributed histiocytes throughout the smears . these cells showed single to multilobated or multiple nuclei ; no nuclear atypia or nuclear grooving was noted . these histiocytes had abundant pale cytoplasm and exhibited numerous intact lymphocytes ( emperipolesis ) and plasma cells [ figure 1 ] . a few histiocytes also showed the presence of neutrophils in their cytoplasm . in some histiocytes , the background had mature lymphocytes , plasma cells , neutrophils , and tingible body macrophages . based on this characteristic cytomorphology smears showing numerous histiocytes with evidence of emperipolesis ( giemsa , 400 ) subsequently , biopsy of a cervical lymph node was done wherein paraffin - embedded sections of lymph node biopsy showed fibrous thickening of the lymph node capsule and an altered nodal architecture . the sinuses were dilated and packed with large histiocytes having abundant pale cytoplasm and phagocytosed lymphocytes ( emperipolesis ) , plasma cells , and occasional neutrophils . shml or rosai - dorfman disease is a rare but well - defined , histiocytic , proliferative disorder of unknown etiology . however , any age group may be affected ; males are affected more than females . the clinical presentation of this entity , as described in the initial publications , consists of painless , bilateral , cervical lymphadenopathy associated with fever , leukocytosis , elevated esr , and hypergammaglobulinemia , but a wide range of extranodal presentation has been noted in recent years . most common extranodal sites involved are the eyes and ocular adnexa , head and neck , upper respiratory tract including the nose , skin , subcutaneous tissue , bone , skeletal muscle , central nervous system , gastrointestinal tract , salivary glands , genitourinary tract , thyroid , breast , liver , kidney , heart , uterine cervix , etc . the presence of human herpes virus 6 genome was demonstrated by in situ hybridization ; relationship with klebsiella , epstein - barr virus , brucella , or cytomegalovirus were also suggested . our case was a young male who presented with multiple cervical and submandibular lymphadenopathy , fever , leukocytosis , hypergammaglobulinemia , and an elevated esr . cytological features of shml usually reveal numerous large histiocytes with abundant , pale cytoplasm , and phagocytosed lymphocytes ( emperipolesis ) . the background typically shows lymphocytes , plasma cells , and occasional neutrophils [ figure 2 ] . benign histiocytes showing intact lymphocytes ( emperipolesis ) , plasma cells , and neutrophils in their cytoplasm ( giemsa , 400 ) histiocytes show positive immunostaining for s100 protein ; cd11c , cd14 , cd33 , and cd68 antigens in cytological smears . differential diagnoses include reactive sinus histiocytosis , malignant histiocytosis , hemophagocytic syndrome , tuberculosis , and lymphoma . in langerhans cell histiocytosis , langerhans cells have grooved and twisted nuclei and the background has eosinophilic microabscess . reactive sinus histiocytosis shows loose clusters of histiocytes , accompanying which are reactive lymphocytes , germinal center cells , immunoblasts , and tingible body macrophages ; emperipolesis is absent . dorfman disease on the basis of the presence of hemophagocytosis , absence of emperipolesis , and the presence of pancytopenia and hepatosplenomegaly . tuberculous lymphadenitis show epithelioid cell granuloma with or without caseous necrosis , which are absent in rosai  dorfman disease . smears from patients with hodgkin 's disease show lymphocytes , plasma cells , histiocytes , eosinophils , and reed  sternberg cells . in rosai - dorfman disease , fnac is a reliable and sensitive means to establish conclusive diagnosis , obviating the need for biopsy .
sinus histiocytosis with massive lymphadenopathy ( rosai  dorfman disease ) is a rare benign disease of unknown etiology presenting with massive lymphadenopathy . 
 these cases can often be misdiagnosed as lymphoma . 
 hence , it is important to distinguish rosai 
 dorfman disease from lymphoma and other causes of histiocytosis because of the different treatment modalities . 
 we report here a case of rosai  dorfman presenting with massive bilateral cervical lymphadenopathy . 
 we conclude that fine needle aspiration cytology is a useful and reliable tool for the diagnosis of rosai - dorfman disease due to which biopsy can be avoided in these patients , thus , reducing inconvenience to patients .