Abstract:

Objective In order to reduce misdiagnosis of patients with malignant pleural mesothelioma (MPM), to explore the clinical characteristics of MPM and analyze the differences between MPM and tuberculous pleural effusion (TPE).Methods The clinical information and data were collected from 17 patients with MPM who hospitalized at Panjin Infectious Disease Hospital in 2010-2017 and were misdiagnosed as TPE. A retrospectively analyzed was conducted to understand the causes of misdiagnosis and to provide preventive suggestions.Results Most of the enrolled patients with MPM were male (70.6%, 12/17), aged more than 40 years old (70.6%, 12/17) and only 1 patient was determined to have a history exposing to asbestos; patients whose lesions located on the right side of lung (52.9%, 9/17) were more common than those whose lesions located on the left side (35.3%, 6/17); the most common symptom was chest pain (82.4%, 14/17) while fever was rare (17.6%, 3/17). The misdiagnosis time was from 6 days to 18 months with average of (80.6±132.6) days. At the first visit to the hospital, the results of exfoliated cells examination and acid fast bacilli examination in the 17 cases with pleural effusion were negative; the tuberculin test (PPD test) results were positive in 8 cases (47.1%) and among them, 2 cases were strongly positive; the blood T-SPOT.TB test results were positive in 6 cases (35.3%). The biochemical examination results of pleural effusion were as follows: the pleural effusion was exudative, and the color was yellow in 11 cases (64.7%); the proportion of lymphocyte was the highest (50% to 86%) in white blood cells (WBC) and it was counted as 1300-7500×10⁶/L (normal value <100×10⁶/L). The following indicators were all increased: the value of lactate dehydrogenase (LDH) was 280-1 520 U/L (normal value <200 U/L) and the average value was ((439.76±301.82) U/L), adenosine deaminase (ADA) increased in 6 cases (35.3%) (32-56 U/L (normal value was 4-24 U/L), with average of ((26.76±11.96) U/L). The carcinoembryonic antigen (CEA) blood test results were normal in all cases while CEA in pleural effusion increased in 2 cases (11.8%) (one was 8.6 μg/L, the other was 9.2 μg/L (normal value ≤5 μg/L). All cases were found to have pleural thickening by CT scan, and pleural thickening was found to exceed 1 cm in 11 cases (64.7%). Finally, the diagnosis of all 17 cases were confirmed by pathological examinations, including 7 cases were confirmed by thoracentesis and pleural biopsy, 9 cases were confirmed by thoracoscopic biopsy, and 1 case was confirmed by thoracotomy biopsy. The pathological findings were epithelioid-type MPM (11 cases, 64.7%). Conclusion Due to lack of specificity on clinical manifestations, laboratory tests and early CT features in MPM patients comparing with those in TPE patients, so they are easily misdiagnosed as TPE. To confirm the diagnosis of MPM, pathological biopsy or surgical biopsy methods are needed.

Key words: Mesothelioma, Pleural neoplasms, Diagnosic errors, Tuberculosis, pleural, Diagnosis, differential