Thoracoscopy in Pleural Malignant Mesothelioma Diagnosis

On the basis of our personal experience in 70 cases (66 pleural effusions) observed during the period January 1984- January 1996 we are here illustrating and discussing the diagnostic role of thoracoscopy in malignant pleural mesothelioma. A histological diagnosis was achieved in 94.2% of cases. The endoscopic appearance was clearly neoplastic (masses, nodules) in 53 patients (75.7%) and simply inflammatory in 17 pachypleuritis in 13 (18.6%) and of diffuse hyperemia in 3 (5.7%). In all cases fluid cytology (diagnostic yield: 18.5%) and needle biopsy (diagnostic yield 17.1%) were performed. The extension of pleural involvement (endoscopic staging according to Boutin) was also determined. In 16 patients (22.8%) a parietal and diaphragmatic involvement (stage Ia) was found. In 40 patients (57.2%) an associated visceral invasion (stage Ib). In 14 cases (20%) a diffuse parietal, visceral and mediastinal extension (stage II). The exam has always been well tolerated with few immediate complications: subcutaneous emphysema (4 cases) and some negligeable parietal bleeding (2 cases).


t years, in e
pert hands allows a correct diagnosis to be made in nearly all cases, thereby equalling the accuracy previously produced only by thoracot- Address of the corresponding author: Gianfranco Tassi MD, Divisione di Pneumologia, Ospedale di Valle Camonica, 25040 Esine (Brescia), Italy.omy (Boutin and Rey 1993).The procedure not only allows adequate and abundant tissue sam- pling for immunohistochemical staining which is essential for differential diagnosis from adeno- carcinoma (Leong a d Vernon-Roberts 1994) but also allows staging of the disease which is a useful prognostic factor and an important ele- ment in deciding therapy (Boutin et al. 1993).

This report aims at illustrating and discussing the diagnostic role of thoracoscopy in mesothe- lioma on the basis of our experience in 70 cases.


MATERIALS AND METHODS

70 cases o pleural malignant mesothelioma were diagnosed at thoracoscopy first in the Pneumol- ogy Division of the Spedali Civili in Brescia (1984)(1985)(

86) and then in the Pn
umology Divi- sion of the Ospedale di Valle Camonica (1987-1996) (Table I), between January 1984 and January 1996.During this period for diagnostic purposes in pleural disease of unknown etiologyb we carried out a total of 470 thoracoscopies so the disease was diagnosed in 14.9% of the diag- nostic examinations.49 of the patients were male (70%) and 21 were female (30%) with a M/F ratio of 2.3/1.Indications for thoracoscopy were pleural effu- sion in 66 patients (94.2%), while the existence of pleural thickening without exudation wa the only anomaly found in 4 (5.8%).The right side was affected in 36 cases (51.4%), th left in 34 (48.6%),there were no bilateral cases.The aver- age age was 61 years (min 41 yrs, max 84 yrs).Anamnesis for occupational exposure to asbes- tos was definitely positive in only 17 (24.2%)cases and negative or not clear in the remaining 53.

All patients underwent pleural fluid cytology and closed pleural biopsy by Cope needle.The day before thoracoscopy, any pleural fluid present was aspirated and pneumothorax was then induced using a Morelli device; intrapleural pressures were determined which together with radioscopic control checked the degree of paren- chymal collapse, according to our usual tech- nique (Tassi and Marchetti 1993).The average amount of air insuttlated was 100-300 ml, which gave a space of at least 5 cm between the lung and the chest wall.

The actual thoracoscopy was always per- formed under local anesthesia (10-15 ml ido- caine 2%), inserting Boutin's rigid thor coscope (Wolf Co., Knittlingen, Germany) connected to a video camera for monitor viewing into the 5th -6th intercostal space on the midaxillary line using a single port.A second point of entry was necessary only in 4 cases in order to reach areas otherwise inaccessible.The entire pleural area was always explored and multiple biopsy samples

(5-10) were taken both in any suspicious areas and in sites apparently without macroscopically evident lesions.In 3 patients with apparently normal visceral pleura and coexistent fibrohyaline parietal plaques, pleural biopsies were inte- grated with samples from the lung parenchyma using a coagulating forceps.

At the end of the endoscopy, when indicated, poudrage was performed using an asbestos-free talc to induce symphysis (2.5- g): 29 patients were so treated.

In all cases a chest tube for drainage (24- 28 Fr) was inserted and left in place for an aver- age of 3 days (min.a few h urs, max 7 days).Since 1992, 39 patients have undergone local preventive radiotherapy 10-15 days after the examination, with a total dose of 21 Gy over 3 days to a depth of 3 cm over an area between 50 and 100 cm 2 centered over each point of entry (Boutin et al. 1995).
THORACOSCOPY IN PLEURAL MALIGNANT MESOTHELIOMA DIAGNOSIS 149 RESULTS
Exploration of the pleural cavity was straight forw

d in 59
atients (84-2%) since in these cases there were no adhesions, whereas in 11 patients (15.8%) complete exploration was made difficult; by the presence of adhesions which, even after lysis with forceps, sometimes partly hindered the procedure.However even in these cases the biopsies taken usually allowed a correct diagnosis to be made.

Most of the lesions observed (Table II) were clearly neoplasti (Fig. 1): isolated nodules or multiple lesions (vegetations; masses; thicken- ings).Diffuse pachypleuritis was found less frequently (Fig. 2) and simple inflammation (Fig. 3) only rarely.Moreover the presence of fibrohyaline plaques with the characteristics of asbestotic plaques was noted in 13 patients (18.6%).

Biopsy allowed the diagnosis of pleural malig- nant mesothelioma in 66 patients (94.2%) and also provided its histological classification (Table III) with a marked prevalence of epithelial type.In 2 cases in which biopsies were insuffi- cient due to extensive adhesions which pre- vented a complete exploration of the cavity diag- nosis was made after thoracotomy.In another 2 cases diagnosis was reached with a second thora- coscopy performed some months later due to the reappearance of the effusion.In all 3 patients submitted to forceps parenchymal biopsy we ob- tained a diagnosis of pulmonary asbestosis with- out complications using a coagulating forceps which insured the aerostasis of the lung therefore avoiding air leak.Thoracoscopy also allowed Boutin cla

ifica- tion
of the disease according to the degree of pleural involvement: in 16 cases (21.8%)only the parietal and diaphragmatic pleura were involved (stage Ia), 40 (57.2%)presented visceral invasion (stage Ib), and 14 (20%) massive invasion of all the pleural surfaces (stage II).

Talc poudrage made in 29 cases achieved a permanent pleurodesis with no recurrence of effusion in 4 patients (83%).

Thoracoscopy was always well tolerated and there were no major complications immediately after the procedure.Minor complications in- cluded subcutaneous emphysema in 4 patients (5.7%) and minor parietal bleeding in 2 (2.8%).Later complications included 3 (4.3%)cases of  neoplastic invasion of the thoracic scar, all of them in the first 31 pati nts not treated by local radiotherapy.This no longer occurred in the remaing 39 who had a radiation therapy.


DISCUSSION

In recent years thoracoscopy has been enjoying a second youth and has become an invaluable method in the diagnosis of pleural effusions in general and mesotheli ma in particular.In ex- pert hands the examination is diagnostic in the vast majority of cases, reducing the need for exploratory thoracotomy which has higher mor- bidity and mortality (Weatherford et al. 1995).

If we compare data regarding the sensitivity of the methods used before thoracoscopy the clear advantage of the latter is striking.Our experience (Table IV), similar in esults to other large case studies, shows that mesothelioma can be diag- nosed by thoracoscopy in 94% of cases: much higher than the 17/18% diagnostic yield of needle biopsy and fluid cytology.

Even thoracoscopy does not however reach 100% sensitivity.The small percentage of false negatives present in all the studies is usually due to the presence of adhesions which cannot be divided endoscopically and which therefore pre- vent a complete exploration or the pleural cavity.

It should be noted that this is usually the case when thoracoscopy is delayed too long and often eventually performed several months after the appearance of an effusion.It can therefore be supposed, and our experience confirms this, that a prompt use of the method in the investigation of pleurisies which have not been diagnosed with other means can further increase sensitivity.

Clearly neoplastic lesions (vegetations; nod- ules; multiple lesions) were present in 75.7% of our cases showing that a generic diagnosis of malignancy at endoscopy is possible in most patients.However there can be more deceptive pictures of simple i flammation or of generic pachypleuritis (1/4 of our patients) and these cases emphasize the need for multiple biopsies from a wide range of sites.

Asbestotic type fibrohyaline plaques (an irreg- ular surface with a 'candle wax drop' appear- ance), which we observed in 13 (18.6%) of our 70 patients are also useful for diagnosis: these plaques found together with clearly neoplastic lesions (nodules or m sses) (Fig. 4) clearly point to a diagnosis of mesothelioma.In fact during our experience in neoplastic pleurisy in 400 tho- racoscopies we have never found these plaques associated with other tumors.Another useful point to rememb r is that when fibrohyaline FIGURE 4 technique of pleurodesis (Walker-Renard et al. 1994).
ts complete efficacy in 83% of the cases avoided the need for painful thoracentesis which also exposes patients to the risk of neoplastic seeding.

Tolerance to the examination was very good, and there were no fatalities which further proves that thoracoscopy, if correctly performed, pre- sents no particular risks or complications.

We can therefore conclude that the role of thoracoscopy in mesothelioma nowadays is un- deniably fundamental, both for diagnostic and therapeutic purposes, and it should be systemat- ically utilized in all suspicious cases.plaques are found but occupational exposure has not been proved, lung biopsy with coagulating forceps can be performed during the same thora- coscopy session and under local anesthesia, thereby demonstrating an eventual asbestosis.

We, like other authors (Rusch 1995), used thoracoscopic staging for therapeutic approach.

In fa t only fairly recently has it been discovered that mesothelioma which has invaded the vis- ceral pleura after primitive involvement of the parietal and diaphragmatic pleura has a much w