Pulmonary mucinous cystadenoma complicated with infection

RATIONALE: Mucinous cystadenoma is a benign tumor that is commonly found in the pancreas, ovaries, or appendix, but is rarely encountered in the lungs. Worldwide, only a few reported cases of these tumors originate in the lungs. Herein, we analyzed the imaging features of a case of pulmonary mucinous cystadenoma (PMCA). To the best of our knowledge, this is the first reported case of PMCA complicated by significant infection. PATIENT CONCERNS: A 57-year-old man was admitted to our hospital with blood in sputum for more than 2 months. Serum laboratory examination showed significantly elevated leukocyte and tumor marker, carcinoembryonic antigen. Enhanced thoracic computed tomography and whole-body positron emission tomography/computed tomography showed a cystic-solid ill-defined mass in the right upper lung. DIAGNOSIS: The tumor was considered malignant, both clinically and radiologically. INTERVENTIONS: The patient underwent right upper lobe tumor resection and mediastinal lymph node dissection. OUTCOMES: Postoperative specimen pathology was diagnosed as PMCA with infection. The patient was not administered any further treatment. The patient was alive without any recurrence or metastasis of the tumor after 2 years of follow-up. LESSONS: Preoperative diagnosis of PMCA with atypical imaging and clinical manifestations is extremely difficult. This is the first reported case of PMCA complicated by a significant infection that was misdiagnosed preoperatively as a malignancy.