Background: The present study is designed to evaluate the role of pleural fluid cytology and pleural biopsy in diagnosing pleural diseases and to study the advantages and disadvantages of thoracocentasis and pleural biopsy. Materials and Methods: We prospectively included 66 consecutive indoor patients over a duration of 1-year. Pleural fluid was collected, cytological smears were made from the fluid. Plural biopsy was obtained in the same patient by Cope′s needle. Adequate pleural biopsy tissue yielding specific diagnosis was obtained in 47 (71.2%) of cases. Results: Tuberculosis was the commonest nonneoplastic lesion followed by chronic nonspecific pleuritis comprising 60% and 33.3% of the nonneoplastic cases respectively and tuberculosis was predominantly diagnosed in younger age group. Majority (70.8%) of malignancy were in the age group of >50-70. Adenocarcinoma was found to be the commonest (66.7%) malignant neoplasm in the pleurae followed by small cell carcinoma (20.8%). Conclusion: Pleural biopsy is a useful and minimally invasive procedure. It is more sensitive and specific than pleural fluid smears.

INTRODUCTION

The pleural space is a potential space between the visceral and parietal layers of the pleurae. The pleural space normally contains 0.1-0.2 ml/kg body weight of fluid. [1] Pleural effusion is an abnormal accumulation of fluid in the pleural cavity. Pleural effusion remains the most common manifestation of pleural pathology. [2] Although a variety of clinical conditions like heart failure, malignancy, pneumonia, tuberculosis may be the cause of a pleural effusion. The possibility of a malignant involvement of pleural cavity should always be considered in difficult to diagnose cases. Since percutaneous access of the pleural space is relatively simple, techniques like pleural biopsy and thoracoscopy have become very popular. However in a developing country like India, where such specialized facilities are available only in Advanced Pulmonary Medicine Centers, pleural fluid analysis and cytology remains the mainstay for diagnosing the various pulmonary diseases. [3]

Analysis of pleural fluid cytology has an important contribution for investigation of patients with pleural effusion. [4] Cytological examination not only helps for diagnosis of cancer but also for staging and prognosis of diseases. [5] Pleural biopsy is helpful to reach an etiological diagnosis of exudative pleural effusion, particularly when malignancy is suspected or when results of detailed pleural fluid study are inconclusive, especially in a set up where thoracoscope is not available. [2] Closed pleural biopsy provides the highest diagnostic yield in cases of pleural tuberculosis and malignancy, the two most important causes of exudative pleural effusion. [6]

The aim of this study is to obtain pleural fluid sample by thoracocentesis and to compare fluid cytology with a pleural biopsy to determine the etiology by various histopathological and cytological tests and to analyze the results.

MATERIALS AND METHODS

We prospectively included 66 consecutive indoor patients over a duration of 1-year. Patients with transudative pleural effusion, pyothorax, chylothorax were excluded. Pleural fluid was collected by thoracocentesis under local anesthesia, cytological smears were made from the fluid. Plural biopsy was done in the same patient by Constantin Cope. [7] Adequate pleural biopsy tissue yielding specific diagnosis was obtained in 47 (71.2%) of cases [Table 1] and [Chart 1 [INLINE:4]]. The cytological smears were stained with Giemsa stain and Papanicolaou stain. Pleural biopsy was stained with Hematoxylin and Eosin staining.{Table 1}

RESULTS

Age range of the patients were 18-84 years with a mean age of 51 years and 66.6% were males. The most common presenting symptom was shortness of breath (95.4%) followed by chest pain (89.4%) and productive cough (69.7%) and 48.5% patients had a history of smoking. Majority of the pleural fluid (69.7%) were hemorrhagic and rest (30.3%) were straw colored.

Tuberculosis was the most common nonneoplastic lesion followed by chronic nonspecific pleuritis comprising 60% and 33.3% of the nonneoplastic cases, respectively. Tuberculosis was the most common nonneoplastic disease in the younger age group (11-30 years) comprising 55.5% of all cases of tuberculosis.

Majority (70.8%) of malignancy were in the age group of >50-70. Adenocarcinoma [Figure 1]a, b and [Figure 2]a,b was found to be the commonest (66.7%) malignant neoplasm in the pleurae followed by small cell carcinoma [Figure 1]c, d and [Figure 2]d (20.8%) and also these were more commonly encountered in male patients.{Figure 1}{Figure 2}

Only one patient (1.5%) suffered from pneumothorax after the pleural biopsy.

True positive - Positive in both biopsy and cytology.

True negative - Negative in both biopsy and cytology.

False positive - Negative in biopsy but positive in cytology.

False negative - Positive in biopsy but negative in cytology.

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DISCUSSION

Thoracocentesis has been a very popular diagnostic as well as therapeutic procedure for tapping pleural effusions and with very few procedural complications. [3] It is usually done through the 2 nd intercostal spaces below the fluid level. [8] Medical thoracoscopy, by a pulmonologist is a safe and effective procedure for the diagnosis and therapy of various pleural diseases, but it is more invasive and expensive procedure, with a risk of complications like pneumothorax. Very few pulmonologist are trained in thoracoscopy and it is available only at selected centers, and furthermore its cost is very high for an economically average person, in a developing country like India. [3] A recent survey has also revealed that even in USA, only 6% of pulmonologists are currently trained in and perform a thoracoscopy. [9] Hence, thoracocentesis still remains a popular diagnostic procedure in cases of pleural effusion.

Gouda et al. compared the diagnostic sensitivity of both Cope′s needle and Abrams LD and found it to be 85% for Cope needle and 57.5% for Abrams needle. [10] However, adequate pleural biopsy tissue yielding specific diagnosis was obtained in 47 (71.2%) of cases by Cope′s needle in this study. Different complications have been noted in patients after pleural biopsy procedure, some of them being pain at the site of biopsy, [11],[12] pneumothorax, [10],[11],[12] and hemothorax.

In their study, Bhattacharya et al. observed that cytological analysis of 3 consecutive samples of patients of pleural effusion increased the diagnosis rate of malignancy. [13] However in the present study, only one sample of the pleural fluid was obtained and compared with pleural biopsy.

In pleura, secondary tumors are more common than the primary tumors. The primary tumor may be pulmonary or extrapulmonary. The common pulmonary tumors infiltrating into the pleurae are squamous cell carcinoma, small cell carcinoma and adenocarcinomas and extrapulmonary neoplasms metastasizing into pleura are usually from breast, ovary, GIT, stomach, and pancreas. [14] Adenocarcinoma is the most common malignancy encountered in the pleural biopsy. [3],[13],[15] The second most common being small cell carcinoma. [3],[13] However, Khan et al. (2011) in their study of 26 malignancies found mesothelioma as the second most common malignancy. In the present study also the most common malignancy metastasizing to pleura was adenocarcinoma [Figure 1]a, b and [Figure 2]a, b (43.7%) followed by small cell carcinoma [Figure 1]c, d and [Figure 2]d (15.6%) and squamous cell carcinoma [Figure 2]c (9.4%) which was quite similar to previous studies. [3],[13]

Combining pleural fluid analysis with pleural needle biopsy can help in the diagnosis and morphological classification of the majority of malignant pleural lesions, leaving around 7-12% undiagnosed cases. [16] Thoracoscopy is the ideal procedure available to directly explore the pleural cavity and visualize the malignancies in early stages, which are confined up to visceral pleura of the lung. However, even after thoracoscopy, around 10% of effusions remain undiagnosed. [17],[18]

CONCLUSION

Pleural biopsy is a useful and minimally invasive procedure. It is more sensitive and specific than pleural fluid smears. In a country like India, where investigations and health facilities are inadequate and cost of treatment is often high, pleural fluid analysis, and cytology should continue to be the first line investigation in patients presenting with pleural effusion. It is not only cost effective but a reasonably safe procedure, which shows reasonably good sensitivity and specificity in diagnosing primary, as well as metastatic pleural malignancies.