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kikuchi - fujimoto disease ( kfd ) is a benign self - limiting disease characterized by fever and lymphadenitis , especially of the neck1,2 ) .
previously , it was thought that some viral infections such as epstein - barr virus ( ebv ) , human herpes virus ( hhv ) , parvovirus b19 , and human t - lymphotropic virus-1 ( htlv-1 ) might cause lymphadenitis in kfd2 ) . on the other hand ,
reports of kfd patients with autoimmune diseases seem to suggest that the pathogenesis of kfd is autoimmune1 - 3 ) . several kfd patients with systemic lupus erythematosus ( sle ) and hemophagocytic lymphohistiocytosis ( hlh )
have been reported in korea , but a kfd patient with autoimmune thyroiditis has not yet been reported4,5 ) . here , we report the case of a 17-year - old female patient diagnosed with kfd and autoimmune thyroiditis
a 17-year - old girl was admitted to a university hospital with lymphadenopathy on the right side of the neck lasting for a week , and she was treated with antibiotics . however , she complained fever , sore throat , and otalgia beginning on the fourth day of hospitalization , and she was transferred to seoul st .
three years prior she had experienced fever with lymphadenopathy on the left side of the neck .
she was admitted to the same hospital , treated with antibiotics , and recovered . at that time
thyroid function tests were normal and the levels of antithyroid antibodies were close to the upper limits of normal .
her blood pressure was 100/70 mmhg , heart rate was 78 beats / min , respiratory rate was 20 breaths / min , and body temperature was 38.4. she had multiple tender lymph nodes on the right lateral side of the neck and in the right supraclavicular area , and the largest lymph node was 32 cm in size .
her laboratory tests showed anemia ( hemoglobin 7.6 g / dl ) , leucopenia ( white blood cell count 2,700/l ) , and elevated levels of erythrocyte sedimentation rate ( esr ) of 70 mm / hr , c - reactive protein of 0.93 mg / dl and lactate dehydrogenase ( ldh ) of 688
thyroid function tests were normal , but antithyroid peroxidase antibodies and antithyroglobulin antibodies were elevated ( table 1 ) . computed tomography of the neck revealed multiple enlarged lymph nodes at levels ii , iii , iv and v on both sides of the neck and in the right supraclavicular area of the neck ( fig .
, she complained of pruritic skin rashes on her lower extremities . despite antibiotic and analgesic treatment ,
the fever persisted , the skin rashes spread to her trunk and upper extremities , her cervical lymph nodes continued to enlarge , and the lymphadenopathy spread to the occipital area . on the sixth day of hospitalization , an excisional biopsy of the enlarged cervical lymph node was performed , and the histopathologic findings were consistent with kfd ( fig .
her fever persisted after the excisional biopsy , so we started the administration of oral prednisolone ( 0.5 mg / kg / day ) on the seventh day of hospitalization . on the ninth day of hospitalization , the fever disappeared and the skin rashes began to subside .
ultrasonography of her thyroid showed heterogeneous echogenicity of the thyroid gland and a solitary nodule .
we diagnosed her with autoimmune thyroiditis on the basis of her family history and the laboratory results .
kfd was first described in 1972 separately by kikuchi6 ) and fujimoto et al.7 ) .
kfd usually occurs in young women between the ages of 20 and 40 years1 ) .
the female to male ratio is 4:11 ) , but some reports from east asia show a relatively lower female to male ratio , 1:1 to 2.28:18 - 10 ) .
kfd commonly manifests as cervical lymphadenitis with fever , but mediastinal , mesenteric , inguinal , or axillary lymph nodes may be involved2,10 ) .
other uncommon symptoms include upper respiratory symptoms , sore throat , weight loss , fatigue , headache , nausea , vomiting , arthralgia , skin rash , and hepatosplenomegaly1,2,9,10 ) .
leucopenia , anemia , elevated esr , elevated serum ldh , or elevated liver enzyme levels have been reported in many cases , although there is no specific laboratory finding indicative of kfd1,2,8 - 10 ) .
fine - needle aspiration cytology ( fnac ) can be used to diagnose kfd11 ) .
however , the diagnostic accuracy of fnac for kfd is about 56% , thus excisional biopsy of the involved lymph node is necessary for the accurate diagnosis of kfd1 ) .
the involved lymph nodes characteristically demonstrate apoptotic necrosis with abundant karyorrhectic debris in the cortical and paracortial areas1,12 ) .
the necrotic lesions are surrounded by many different types of histiocytes including plasmacytoid dendritic cells , and the number of transformed lymphocytes with immunoblast morphology is increased in some cases1,12 ) . however ,
neutrophils and eosinophils are characteristically absent , and plasma cells are few or absent1,12 ) .
lymphocytes are predominantly t cells rather than b cells , and the t cells are predominantly cd8 + t cells rather than cd4 + t cells1,12 ) .
the cause and pathogenesis of kfd remains unclear , and two hypotheses have been suggested : a viral infection hypothesis and an autoimmune hypothesis1 ) .
prodromal upper respiratory symptoms , the lack of response to antibiotic therapy , atypical lymphocytes in some cases , t cell zone expansion with immunoblast proliferation , and elevated interferon- support the hypothesis of a viral etiology1 ) .
many viruses including ebv , cytomegalovirus , hhv , parvovirus b19 , and htlv-1 were suggested as the causative organism , but a causal relationship has not been confirmed2 ) .
in contrast to the pathologic findings of kfd , viral lymphadenitis has less prominent histiocyte infiltration , more neutrophils and plasma cell proliferation , and cd4 + t cell predominance1 ) .
based on the clinical similarity ( fever , lymphadenitis , skin rash , arthralgia ) and histologic similarity ( paracortical necrosis with karyorrhectic debris and inflammatory cell responses ) of kfd and sle , an autoimmune etiology was suggested3,12 ) .
in addition , continuing reports of autoimmune diseases in kfd patients and therapeutic response to steroids and intravenous immunoglobulins in kfd patients with autoimmune diseases also support the autoimmune origin of kfd3 ) .
kfd cases with sle , hlh , sjgren syndrome , adult onset still 's disease , and polymyositis have been reported from several areas of the world , and the autoimmune diseases developed before , after , or simultaneously with kfd2 - 5,10,13 ) .
however , only a few kfd cases with autoimmune thyroiditis have been reported3,14 ) . until now , a case of kfd with autoimmune thyroiditis has not been reported in korea .
we diagnosed this 17-year - old girl with kfd on the basis of the histopathologic findings of the excised lymph node , and autoimmune thyroiditis was diagnosed on the basis of the presence of antithyroid antibodies .
kfd is a self - limiting condition and usually resolves in one to six months with recurrence rates of 3 to 4%1,9 ) .
steroids can be used to treat patients with complicated or systemic kfd , recurrent kfd , prolonged fever , and symptoms lasting more than two weeks despite treatment with nonsteroidal antiinflammatory drugs14 ) . in our case ,
lymphadenopathy spread to the occipital region and the fever remained after the excisional biopsy , so we decided to treat her with oral steroids , and there was a dramatic clinical effect .
to date , several kfd cases associated with various types of autoimmune diseases have been reported4,5,13,15 ) .
clinicians should consider kfd when lymphadenopathy arises in patients with autoimmune disease , and should also keep in mind the possibility of autoimmune disease in kfd patients .
however , it is not clear whether kfd and autoimmune diseases have a direct association or occur concomitantly by chance2 ) .
kikuchi - fujimoto disease ( kfd ) is a benign self - limiting disease characterized by fever and lymphadenitis . 
 the etiology and pathogenesis of kfd is unclear . 
 however , two hypotheses have been suggested : a viral infection hypothesis and an autoimmune hypothesis . 
 several kfd patients with various types of autoimmune diseases have been reported , and these reports support the hypothesis for autoimmune pathogenesis of kfd . here , we report the case of a 17-year - old female patient diagnosed with kfd and autoimmune thyroiditis . 
 this case serves as additional evidence that the etiology of kfd is autoimmune origin .