immunoglobulin g4-related disease ( igg4-rd ) an autoimmune disease characterized lymphoplasmacytic tissue infiltration with a predominance of igg4-positive plasma cells . although igg4-rd can affect any organ , the majority of cases have been reported involving the biliary tract or pancreas . a 58-year - old man visited our outpatient clinic with a seven - day history of dyspnea . , he had undergone a bilateral thyroidectomy with modified radical neck dissection at another hospital due papillary thyroid cancer . he had been taking 100 micrograms ( mcg ) of levothyroxine once daily for three years . during the pre - operative evaluation of his thyroid cancer at the other hospital , a small to moderate amount of pericardial effusion was noted on the transthoracic echocardiogram ( tte ) . because the patient did not have any symptoms of pericardial effusion , the cardiologist recommended follow - up ttes every six months . the initial physical exam on the first day of hospitalization revealed a blood pressure of 130/60 mm hg , pulse rate of 92 beats per minute , respiratory rate of 18 breaths per minute , body temperature of 37.0 , and oxygen saturation of 96% while the patient was breathing ambient air . bilateral pretibial edema was observed , and decreased lung sounds were heard at the bilateral lower lung fields . findings of laboratory tests on the first day of hospitalization indicated a normal complete blood count , as well as normal levels of blood urea nitrogen , creatinine , total protein , albumin , aspartate aminotransferase , alanine aminotransferase , and electrolytes . the blood levels of triiodothyronine , thyroxine , and thyroid - stimulating hormone were within normal limits ( 0.69 ng / ml , 1.51 ng / dl , and 1.93 iu / ml , respectively ) . the levels of serum anti - nuclear antibody , anti - deoxyribonucleic acid enzyme linked immunosorbent assay , anti - smith antibody , p - antinuclear and antineutrophil cytoplasmic autoantibodies ( anca ) , c - anca , anti - scl 70 , and lupus anticoagulant were negative . the patient 's blood level of c - reactive protein was 21.5 mg / l , erythrocyte sedimentation rate was 33 mm / hr , complement 3 ( c3)/c4 was 131.5/31.09 mg / dl , and lactate dehydrogenase ( ldh ) was 213 three sputum acid - fast bacillus ( afb ) smears and cultures were negative , and interferon gamma ( ifn- ) release assay tests for tuberculosis were also negative ( nil : 0.06 , tb ag : 0.11 , mitogen : 14.87 ) . we detected bilateral pleural effusion with loculation along the right minor fissure with moderate cardiomegaly on the patient 's chest radiograph ( fig . 1a ) . on the tte from the first day of hospitalization , we observed constrictive physiology with a small amount of organized pericardial effusion ( fig . pericardial effusion with mild fluorodeoxyglucose uptake was observed on positron emission tomography - computed tomography , likely due to inflammatory processes ( fig . furosemide ( 20 mg twice daily ) and spirolactone ( 12.5 mg twice daily ) were prescribed to control the patient 's dyspnea and pretibial pitting edema , and other laboratory studies were conducted to detect the cause of the constrictive pericarditis . to diagnose and treat the patient 's idiopathic constrictive pericarditis , we performed a pericardial effusion drainage and biopsy on hod 3 . on the pericardial effusion study , the test results showed 4 g / dl of protein , 2.5 g / dl of albumin , 123 iu / l of ldh , 142 mg / dl of glucose , and 43.7 mycobacterium tuberculosis complex polymerase chain reaction ( pcr ) of the pericardial fluid , afb smears , and culture were all negative . histopathology of the pericardial biopsy revealed mild chronic inflammatory cell infiltration with fibrosis , but there was no evidence of igg4 cell infiltration . after drainage of the pericardial effusion , we observed a temporary improvement of dyspnea , but it was aggravated on hod 7 . histopathology findings of the pericardiectomy revealed a diffuse coating of fibrinous exudate with mild lymphocytic infiltration with igg4-positive cells ( 30/hpf , igg4/igg ratio : 5% ) ( fig . 4 ) . therefore , we diagnosed pericarditis caused by igg4-rd , and prednisolone ( 40 mg ) was initiated to treat the persistent mild dyspnea after the pericardiectomy . as the patient 's symptoms disappeared , he was discharged and during follow - up , we observed resolution of the pericardial effusion and bilateral pleural effusion on the chest x - ray and tte ( figs . immunoglobulin g4-related disease is an autoimmune disease that may involve any organ , characterized by a lymphoplasmacytic infiltrate enriched in igg4-positive plasma cells , and variable degrees of fibrosis.1 ) target organ biopsy and histopathology are the most important diagnostic methods . for most tissues , the diagnosis is made from 30 to 50 igg4-positive cells / hpf.2 ) sometimes serum igg4 levels are elevated in igg4-rd , but serum igg4 concentrations are neither sufficiently sensitive nor specific for diagnosis of this disease.3 ) the natural course of igg4-rd is not well - defined . generally , it is effective to treat igg4-rd with moderate to high doses of steroids . some previous reports have demonstrated that igg4-rd spontaneously regressed without treatment.4 ) however , when vital organs are involved , aggressive treatment is needed because igg4-rd can lead to serious organ dysfunction and failure.5 ) constrictive pericarditis occurs in approximately 2 - 3% of cases after pericarditis,6 ) and 40 - 50% of cases are idiopathic in origin.7 ) while the most common cause is thought to be viral infection , the association of viral infection with igg4-rd is a source of much debate . there is a lack of consensus regarding the incidence , etiology , and treatment of igg4-rd . several case reports have been published worldwide , including a case of a 78-year - old male with constrictive pericarditis confirmed to have igg4-rd after pericardiectomy,8 ) and a second case of a 29-year - old female with lung en - trapment and constrictive pericarditis caused by igg4-rd.9 ) after pericardiectomy , symptoms disappeared in the first patient and no further treatment was necessary . the second patient required prednisolone ( 40 mg / day ) for 2 weeks with gradual tapering . iu / l , and therefore , within the lower limit of diagnosis for tuberculous pericarditis ( tb pericarditis ) . however , he did not have any clinical symptoms of tb pericarditis such as fever , night sweating , or weight loss . moreover , tb pcr , afb smear , and ifn- release assay testing for tuberculosis were all negative . as tuberculosis is endemic in south korea , and tb pericarditis is the second most common cause of constrictive pericarditis after idiopathic pericarditis,9 ) igg4-rd can easily be misdiagnosed as tb pericarditis since pericardial fluid ada levels may be increased over 40 iu / l . consequently , this can lead to a prolonged use of tb medication.10 ) the first pericardial biopsy of the patient did not reveal any igg4-positive cells . however , the pericardiectomy histopathology was positive for igg4-positive cells . we hypothesize that focal infiltration of igg4 cells in the pericardium may have resulted in the initial false negative result .
immunoglobulin g4-related disease ( igg4-rd ) can involve any organ . 
 the majority of reported cases involve igg4-rd of the biliary tract or pancreas , while only two cases of pericarditis have been reported . 
 a 58-year - old man visited the outpatient clinic of our institution with a seven - day history of progressive dyspnea . based on his transthoracic echocardiogram and transesophageal echocardiogram , 
 he was diagnosed with constrictive pericarditis . 
 the histopathology of his pericardiectomy revealed the cause of constrictive pericarditis to be igg4-rd . 
 prednisolone ( 40 mg ) was initiated after the pericardiectomy . 
 as the patient 's symptoms resolved , he was discharged and followed - up on an outpatient basis . 
 this is the first case report of constrictive pericarditis caused by igg4-rd in korea .