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Brief Report

Diagnosis of a Pleural Mesothelioma by Transbronchial Needle Aspiration/Biopsy of a Mediastinal Lymph Node

Casoni, Gian Luca MD; Bigliazzi, Caterina MD; Vailati, Paolo MD; Gurioli, Carlo MD; Poletti, Venerino MD

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doi: 10.1097/01.lab.0000130636.18770.90
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Abstract

Clinicoradiologic suspicion of malignant mesothelioma can be difficult to confirm cytohistologically. The radiologic manifestations tend to be those of pleural effusion and/or pleural thickening. Pleural effusions are initially investigated by thoracentesis. A positive diagnosis by pleural fluid cytology has been reported as low (26%).1,2 Pleural biopsy in the presence of a pleural effusion has been performed using a reverse bevel needle without image guidance with a sensitivity of 21% to 43%3 for the detection of malignant mesothelioma. However, we report, for the first time, a case of diagnosis of pleural malignant mesothelioma with transbronchial needle aspiration (TBNA) from a mediastinal lymph node through a flexible bronchoscope.

CASE REPORT

The patient was a 68-year-old woman. She was admitted to hospital after a 5- to 6-day history of increasing dyspnea with chest pain and right pleural effusion.

On physical examination, the vital signs were within normal limits except for a temperature of 37.4°C and O2 saturation of 91% on room air. Coarse crackles were present over the right lower lung field. The cardiovascular examination revealed normal heart sounds without any rubs or murmurs.

Chest x-ray and computed tomography of the chest showed a pleural effusion in the right lower region with mediastinal lymphadenopathy. The cytologic examination of the effusion (by thoracentesis) did not show any malignant cells. Biochemical analysis of the effusion was normal. Bacteriologic examinations, staining, and culture of the fluid were negative. Flexible bronchoscopy with TBNA (with a 19-gauge needle) from mediastinal lymph node was performed. The cytologic examination of material obtained by transbronchial needle aspiration revealed malignant mesothelioma.

The diagnosis was confirmed histologically on the specimens obtained through transbronchial needle biopsy performed during the same bronchoscopy (Fig. 1). In particular nests of epithelioid, neoplastic cells embedded in a background rich in lymphocytes were depicted by antibodies against cytokeratin 5/6 and calretinin.

FIGURE 1.
FIGURE 1.:
Immunohistochemistry study of the tumor cells, calretinin-positive. Clusters of neoplastic cells embedded in a lymphocyte-rich background stained with monoclonal antibodies against calretinin (APAAP, ×40).

DISCUSSION

Pleural biopsy in the presence of a pleural effusion is normally performed using a reverse bevel needle without image guidance with a sensitivity of 21% to 43%3 for the detection of malignant mesothelioma or thoracoscopy in which a higher diagnostic yield is expected. However, we reported for the first time the diagnosis of malignant mesothelioma with TBNA from a mediastinal lymph node. TBNA has been proved to be a valuable tool in the diagnosis and staging of bronchogenic carcinoma,4,5 and it has been also investigated for mediastinal and subcarinal lymphadenopathy, getting simultaneous diagnostic and staging information with a lower complication rate than mediastinoscopy.6 In the studies using TBNA, the rate of adequate materials obtained has been reported as 50% to 84% when using 18- to 19-gauge needles. TBNA has a success rate of 32% to 72% in the diagnosis of any disease. This percentage was 64% to 85.7% for individuals in whom adequate materials were taken.7,8 There was no evidence in the literature for the diagnosis of malignant mesothelioma with TBNA from mediastinal lymph node. Unfortunately, because the adenocarcinoma of the lung with pleural involvement frequently resembles pleural epithelioid mesothelioma clinically as well as macroscopically as microscopically, the differential diagnosis could be problematic, especially when the cytohistologic material was obtained by TBNA. In fact, microscopically, both tumors can form papillary structures. The tumor cells in an epithelioid mesothelioma are usually more uniform, cuboidal, and less crowded than the tumor cells in adenocarcinoma, which are more pleomorphic, columnar, and crowded with nuclear molding.

Therefore, special stains, including the standard panel of immunohistochemical markers used for the diagnosis of mesotheliomas and/or electron microscopy, are essential for the differential diagnosis of malignant mesothelioma and adenocarcinoma9 also when the specimens are obtained by transbronchial needle (19-gauge) aspiration/biopsy.

We conclude that TBNA using histologic needles through a flexible bronchoscope is a valuable tool in the differential diagnosis of intrathoracic adenopathies, including the malignant mesothelioma. This method seems to be rapid, safe, and effective for the diagnosis of intrathoracic lymph nodes before other invasive procedures.

REFERENCES

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Keywords:

mesothelioma; transbronchial needle aspiration; fiberoptic bronchoscope; mediastinal lymph node

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