A rare pleural mucinous cystadenocarcinoma mimicking loculated empyema initially: A case report
A 35-year-old male presented with upper respiratory symptoms and dyspnea for 3 days, along with right flank pain. He had been smoking for around 10 years. There was no significant past medical history. Laboratory tests showed an elevated white blood cell (WBC) count of 182,000/mm3 and C-reactive protein (CRP) level of 12.4 mg/dL. Chest radiograph revealed a large soft tissue opacity in the medial aspect of right lower hemithorax. It had smooth lobulated lateral margins whereas the medial margin merged with the mediastinal silhouette []. Contrast-enhanced chest CT showed a large, well-defined, ovoid, non-enhancing low attenuation lesion with mild peripheral rim-like enhancement in right posterior hemithorax (maximal diameter about 10 × 8 cm). Adjacent to the intrapleural low attenuation lesion, there was peribronchial consolidation in right posterior basal lung containing low attenuation area and fluid bronchogram with focal communication into adjacent pleural space [Figure and ]. Small amount of free pleural effusion was also detected. Neither mediastinal nor hilar lymphadenopathy was detectable. Initial CT diagnosis was a large loculated empyema with adjacent focal necrotizing pneumonia. Insertion of chest tube was performed for the drainage of pleural fluid and the resultant pleural cytology showed malignant cells. With the impression of intrapleural cystic malignancy, patient underwent open thoracotomy with decortication and right lower lobe (RLL) wedge resection. At surgery, a huge gelfoam like mass was found mainly occupying the pleural space in right posterior hemithorax. The specimen including pleural cystic mass and subpleural parenchyma, was of size 10 × 7 × 3 cm. Histologically, most of the tumor was composed of dissecting mucin material. The peripheral portion of the tumor showed mucinous epithelial cell nests with stratification and mild nuclear atypia. The mucinous epithelial cells had immunoreactivity for cytokeratin 7 (CK7) []. Photomicroscopic image revealed the tumor cells in fibrotic tissue. Mucinous material was attached to pleural fibrotic tissue []. Follow-up chest CT and [18]F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-CT were performed a couple of weeks after the operation for the evaluation of residual lesion or extrathoracic primary site of metastasis. Imaging findings revealed remnant subpleural multiloculated cystic lesion in RLL, with postoperative changes along the resection site. There was no evidence of extrathoracic malignancy []. Patient received four cycles of gemcitabine and cisplatin chemotherapy. But the residual cystic mass in RLL increased on the follow-up chest CT scan after 7 months []. Reoperation with RLL wedge resection of the growing intrapulmonary cystic mass was done and pathological examination confirmed intrapulmonary mucinous cystadenocarcinoma. In 1 year follow-up after postoperative radiotherapy, the patient is stable.