A Case of Immunoglobulin G4-Related Disease Presenting as a Pleural Mass
A 66-year-old male was referred from a local clinic with one-week history of cough and sputum, and abnormal chest X-ray findings. He was a current smoker (one pack per day for 40 years) and had been diagnosed as Alzheimer type dementia. Medications for the dementia included donepezil, sodium valproate and quetiapine. He had no history of diabetes, hypertension and tuberculosis. He denied body weight loss or night sweating. He had no pleuritic chest pain or dyspnea.\nOn admission, he was acutely ill-looking. Blood pressure was 120/80 mm Hg, body temperature was 37.5℃, pulse rate was 66/min, and respiratory rate was 20/min. The lymph node in the neck was not palpated. Physical examination of the chest revealed crackle on right lower lung field but heart sound was normal without murmur. Complete blood count results were hemoglobin 12.7 g/dL, white blood cell (WBC) count 11,750/µL (neutrophils 76%, lymphocytes 21%, monocytes 2%, and eosinophils 1%), and platelet count 309,000/µL. C-reactive protein (CRP) was 34.5 mg/L (reference, 0.00-5.0 mg/L). Liver function test, blood urea nitrogen and glucose were normal. Urine analysis showed no abnormalities. Gram staining with culture, acid fast bacilli (AFB) smear and polymerase chain reaction for AFB of sputum were all negative. The urine pneumococcus antigen was also negative.\nChest X-ray revealed a pneumonic infiltration at right lower lobe (RLL) and a pleura-based mass at right upper hemithorax (). Chest computed tomography (CT) scan showed a consolidation in RLL and a 3.0×1.3 cm-sized ovoid shaped pleural mass with contrast enhancement surrounding normal lung parenchyma with clear margin ().\nWe started antibiotic therapy with a third-generation cephalosporin and macrolide considering the consolidation at RLL as pneumonia. After the treatment the respiratory symptoms and the consolidation on chest X-ray gradually improved. WBC count and CRP level also normalized. However, the pleural mass remained unchanged. We then performed video-assisted thoracoscopic surgery for the lesion. Grossly, the mass consisted of oval-shaped soft tissues 3.0×2.0×1.5 cm in size. Histopathologic examination revealed dense and diffuse lymphoplasmacytic infiltration, storiform fibrosis and some eosinophilic infiltration (). Immunohistochemical staining revealed numerous IgG and IgG4 positive cells (>50 per high power field) (). With the final diagnosis of IgG4-related disease, we then examined the serum IgG4 level, which was increased to 148.0 mg/dL (reference, 6.1-121.4 mg/dL). To identify possible synchronous lesions, we performed otolaryngologic examination and abdominal CT scan and no extrathoracic lesions were evident. The patient was discharged without further treatment at hospital day 14 and has been followed-up at an outpatient clinic without evidence of recurrence.