Correlation between computed tomography of the chest and medical thoracoscopic fi ndings in primary pleural tumors

1687-8426 © 2014 Egyptian Journal of Bronchology DOI: 10.4103/1687-8426.137349 Introduction Malignant pleural mesothelioma (MPM) is an aggressive tumor arising from the mesothelial cells lining the pleural cavity. Th e incidence of MPM is increasing worldwide, and it is expected to increase in the next 10–20 years as a result of widespread exposure to asbestos in the past decades [1]. MPM usually develops on the parietal pleural surface and later on spreads to the visceral pleura. Visceral pleural involvement indicates a more advanced stage of the disease and is therefore an important prognostic factor [2].


Introduction
Malignant pleural mesothelioma (MPM) is an aggressive tumor arising from the mesothelial cells lining the pleural cavity.Th e incidence of MPM is increasing worldwide, and it is expected to increase in the next 10-20 years as a result of widespread exposure to asbestos in the past decades [1].MPM usually develops on the parietal pleural surface and later on spreads to the visceral pleura.Visceral pleural involvement indicates a more advanced stage of the disease and is therefore an important prognostic factor [2].
Computed tomography (CT) scans of the chest are now routinely used for diagnosing, staging, and follow-up of patients with MPM.CT features of MPM are characteristic but not pathognomonic.A variety of benign and malignant diseases may cause pleural abnormalities that resemble MPM.The most common causes are metastatic carcinoma, tuberculous pleurisy, empyema, and asbestosrelated advanced pleural abnormalities.The most helpful signs in distinguishing malignant from benign pleural diseases in chest CT are pleural rind, nodular pleural thickening, pleural thickening greater than 1 cm, and mediastinal pleural involvement [3].
Key CT fi ndings that suggest MPM include unilateral pleural eff usion, nodular pleural thickening, and interlobar fi ssure thickening.Growth typically leads to tumoral encasement of the lung with a rind-like appearance.Calcifi ed pleural plaques are found on CT in ∼20% of patients with MPM and may become engulfed by the primary tumor, causing the tumor to mimic calcifi ed MPM.Th ere is also frequent contraction of the aff ected hemithorax with associated ipsilateral mediastinal shift, narrowed intercostal spaces, and elevation of the ipsilateral hemidiaphragm [4].
CT scan-guided cutting-needle pleural biopsy, performed by a radiologist, is a promising technique for sampling the pleura, because it can improve diagnostic sensitivity to about 80% for pleural malignancy [5].
Th e accurate diagnosis of mesothelioma is made on histopathological examination.However, diagnosis can be diffi cult because mesothelioma is a very heterogeneous cancer that creates various misleading histopathological pitfalls.Moreover, the pleura is a common site for metastatic disease [6].

Correlation between computed tomography of the chest and medical thoracoscopic fi ndings in primary pleural tumors
Tarek Safwat a , Samar Sharkawy a , Amr Shoukri a , Suzan Mohamed b Background Malignant pleural mesothelioma ( MPM) is an aggressive tumor arising from the mesothelial cells lining the pleura.It commonly presents with unilateral pleural effusion with variable degree of pleural thickening and nodularity.MPM usually develops on the parietal pleura, and involvement of the visceral pleura indicates more advanced stage.Treatment of MPM should not be started before correct diagnosis and staging with computed tomography (CT) and thoracoscopy.

Aim of the study
The aim of this study was to assess the correlation between fi ndings on chest CT and those on thoracoscopy and to evaluate the sensitivity of chest CT to identify malignant pleural lesions.

Patients and methods
Patients with suspected MPM and indicated for medical thoracoscopy for diagnostic confi rmation were enrolled in the present study.Twenty patients with confi rmed diagnosis after tissue biopsies with medical thoracoscopy were selected.Comparison and correlation between CT fi ndings and medical thoracoscopic fi ndings were made.

Results
Thoracoscopy showed parietal pleural invasion in all patients, whereas noncontrast chest CT showed parietal pleural lesions in 14 patients (70%).Visceral pleural involvement was evident in 13 patients (65%) on thoracoscopy, but chest CT detected only one case (5%) with visceral pleural involvement.Three patients (15%) were found to have fi brous septations on thoracoscopy, compared with only one patient (5%) on chest CT.The sensitivity of noncontrast chest CT in the detection of MPM was 70%.
rigid thoracoscopy).Abnormal (suspicious) areas were biopsied.Th e appearance of the parietal and visceral pleural surfaces and the extent of their involvement were assessed visually through the thoracoscope.

Statistical analysis
Quantitative data were represented as mean (± SD) and qualitative data as number and percentage.Data entry and statistical analysis were performed using SPSS for Windows, version 20.0 (SPSS Inc., Chicago, Illinois, USA).

Results
Th is study enrolled 20 patients with MPM with a mean age of 62.3 ± 7.43 years; 12 patients were male (60%) and eight were female (40%); 55% of all patients were nonsmokers and 45% were smokers; history of occupational or residential exposure to asbestos was positive in 35% and negative in 65% of the patients.Demographic data of the included patients are displayed in Table 1.
Cytological examination of the pleural fl uid was found to be positive for malignant cells in four patients, representing 20% of the patients, and negative in 16 patients (80%) (Table 2).
In the studied population 14 patients (70%) presented with massive pleural eff usion and six patients (30%) presented with moderate pleural eff usion (Table 3).Th e pleural eff usion was considered moderate if the eff usion reached the fourth intercostal space on plain chest radiograph and as massive if it reached the second space.
Th oracoscopy is the preferred diagnostic procedure when mesothelioma is suspected; allows complete visual examination of the pleura, multiple, deep, and large biopsies (preferably including fat and/or muscle to assess tumor invasion), and provides a diagnosis in 90% of cases [1].
In patients with only fl uid appearance on CT scan, thoracoscopy should be the fi rst method used to improve the chances for a fi nal diagnosis.For some cases, an additional advantage of thoracoscopy is that diagnostic and therapeutic aims, such as drainage and pleurodesis, can be achieved in a single session [7].

Aim of the study
Th e aim of this study was to assess the correlation between fi ndings on chest CT and those on thoracoscopy, and to evaluate the sensitivity of CT chest to identify malignant pleural lesions.

Patients and methods
Th is prospective study was conducted in Abbassia Chest Hospital and included 20 patients with MPM.Patients were included when MPM was suspected and the patient was made to undergo medical thoracoscopy for tissue biopsy and diagnostic confi rmation.All the patients had to give informed written consent.Patients with general contraindications to thoracoscopy (e.g.unstable angina, left ventricular failure, uncontrolled hypertension, bleeding tendency, etc.) or with no confi rmation of MPM after pathological examination of thoracoscopic pleural biopsies were excluded.
All patients were subjected to thorough history taking, clinical examination, routine laboratory investigations, and CT scan of the chest without contrast.Pleural fl uid cytological analysis was performed and medical thoracoscopy performed under local anesthesia (using the Richard Wolf rigid thoracoscopy; Richard Wolf, Germany).CT fi lms were reread.Comparison between fi ndings on CT and those on medical thoracoscopy with statistical analysis was carried out.

Medical thoracoscopy
Twenty patients were given local anesthesia with 15 ml of 2% lidocaine.Th e procedure was performed in lateral decubitus position with the aff ected side upward under local anesthesia with 2% lidocaine and analgesia.Th e skin was sterilized, followed by incision and blunt dissection in the appropriate intercostal space to enter the pleural space.A 7 mm trocar was then inserted, and a 0° telescope was inserted through it and connected to a video camera; the pleural space was then carefully inspected through the thoracoscope (Richard Wolf Visceral pleural lesions were detected by thoracoscopy in 13 patients with mesothelioma, but CT scan detected abnormalities in the visceral pleura in only one patient (Table 4, Fig. 1).
Th e thoracoscope could reveal lesions in the costal pleura in all cases of mesothelioma, but chest CT could reveal changes in the costal pleura only in 14 patients (Table 5, Figs 2 and 3).
Th e thoracoscope was able to show lesions in the diaphragmatic pleura in seven (40%) patients with mesothelioma, but chest CT did not show any lesions in the diaphragmatic pleura (Table 6).
Th ree patients (15%) were found to have fi brous septations between visceral and parietal pleura on thoracoscopy, whereas in only one of these patients (5%) fi brous septations were detected on chest CT (Table 7, Fig. 4).
Th e sensitivity of noncontrast CT scan of the chest for the detection of mesothelioma in this study was 70%; CT was able to detect pleural lesions suggestive of malignancy in 14 cases (Table 9).

Discussion
Th e frequency of MPM has greatly increased in the past three decades; it is a tumor of great clinical, epidemiologic, and therapeutical interest.Th erapy should not be started before the tumor has been Visceral pleural nodules seen by medical thoracoscopy and not detected by computed tomography scan of the chest.Our study included 20 patients with MPM with confi rmed pathological diagnosis: 12 male and eight female patients.Fourteen patients presented with massive pleural eff usion and six had moderate pleural eff usion.CT fi ndings in these patients wer e analyzed.Th e results were compared with the fi ndings on medical thoracoscopy.
Th is is in accordance with the results of the study by Bergonzini et al. [8], which was conducted on 26 patients with CT fi ndings of MPM.In this study the authors compared thoracoscopy and CT fi ndings in the assessment of neoplastic spread to the parietal (stage IA) and/or visceral (stage IB) pleura and reported that, if the suspected MPM is classifi ed as stage II , III, or IV, thoracoscopy should be used only for histologic confi rmation.Conversely, in stages IA and IB, thoracoscopy, besides histology, should be used to confi rm malignant spread to the visceral pleura [8].
Similar results were found in the study by Boutin et al. [2], which was conducted in Marseille, France, on 188 patients with MPM between 1973 and 1990, and aimed to assess the main prognostic factors of the disease.All patients had undergone thoracoscopy with endoscopic description of the lesions, and multiple biopsies were taken.Analysis of the main clinical, histopathological, endoscopic, and radiological (including CT scan) parameters was performed.He demonstrated that thoracoscopy allowed early diagnosis of the disease and a subdivision of stage I into stage IA (with normal visceral pleura) and stage IB (with invaded visceral pleural): Median survivals are 32.7 and 7 months, correctly diagnosed and staged with thoracoscopy and CT [8].
Medical thoracoscopy has proved to be a safe tool in establishing diagnosis in patients with undiagnosed exudative pleural eff usions [9].
Th oracoscopy allows the operator the advantage o f visualizing the pleural cavity, including the diaphragmatic and visceral pleura, as well as the lung, which gives a chance to gain good information on the extent of the disease; in addition, it allows adequate tissue sampling [10].
Computed tomography scan of the chest showing right parietal pleural thickening and medical thoracoscopy showing thickened nodular parietal pleura .

Fig. 3
Pleural adhesions detected by medical thoracoscopy and not seen by chest computed tomography .
Th is is also in accordance with the study by Yilmaz et al. [14], which was conducted in Izmir (Turkey).Th e aim of that study was to determine the signifi cance of diff erent CT fi ndings for the diff erential diagnosis of benign and malignant pleural diseases.CT fi ndings of 146 patients with proven pleural diseases were reviewed; 59 cases were malignant and 87 had benign pleural disease.CT fi ndings that were helpful in distinguishing malignant from benign pleural disease were: (a) Pleural nodularity, (b) Rind, (c) Mediastinal pleural involvement, and (d) Pleural thickening greater than 1 cm.

Acknowledgements Confl icts of interest
Th ere are no confl icts of interest.
respectively.Th erefore, thoracoscopy is necessary in the staging of malignant mesothelioma [11].
In the present study and in the assessment of costal and diaphragmatic pleural invasion, chest CT detected 14 patients with costal pleural thickening (70%) and four patients with costal pleural nodules (20%).Medical thoracoscopy detected 16 patients (80%) with costal pleural thickening and 20 patients with pleural nodules (100%).With regard to diaphragmatic pleura, there were seven cases with diaphragmatic pleural nodules (35%) and one case with diaphragmatic pleural thickening (5%) detected by medical thoracoscopy, whereas chest CT was not able to identify any diaphragmatic pleural lesions.CT was able to detect 14/16 patients with costal pleural thickening (87.5%).
But there was a signifi cant diff erence between CT and medical thoracoscopy in the detection of abnormalities in the diaphragmatic pleura.
Th ese results correlate with those of Metintas et al. [3], whose study was conducted in the Department of Chest Diseases, Osmangazi University, Turkey, on 215 patients: 99 with MPM, 39 with metastatic pleural disease, and 77 with benign pleural disease.In the chest CT of patients with MPM, pleural nodules were detected in 28% of the studied group and pleural thickening in 46%.
In another study conducted by Maasilta et al. [12] in the Department of Pulmonary Medicine, Helsinki University, Finland, 35 CT scans with contrast medium enhancement of the thorax and upper abdomen of patients with MPM were correlated with the fi ndings on thoracotomy (28 patients), thoracoscopy (two patients), or autopsy (fi ve patients).It showed that CT scans of all patients showed pleural thickening with contrast medium enhancement (100%), whereas in our study it was detected in only 70% [12].
In the present study chest CT detected one case with fi brous septations between the visceral and the parietal pleura (5%), whereas medical thoracoscopy identifi ed three cases (15%) with pleural adhesions.Th e sensitivity of CT scan of the chest for detection of pleural septations was only 33% in our series.
Th oracic CT has been studied by Mason et al. [13] to predict pleural adhesions.Th ey reported a limited accuracy of CT scans, with a sensitivity of 46% and specifi city of 38% on a lesion-by-lesion basis [13].
Th e CT fi ndings of the 20 patients included in this study were reviewed by a radiologist blinded to the pathological diagnosis in an attempt to assess the sensitivity of the noncontrast chest CT to identify