Diagnostic accuracy of bronchial brush cytology and the added value of immunohistochemistry and fluorescence in situ hybridization of pulmonary neuroendocrine tumors

Role of Immunocytochemistry in the Cytological Diagnosis of Pulmonary Tumors

Pulmonary cytology is a challenging diagnostic tool, and it is usually evaluated considering medical history and radiological findings in order to reach an accurate diagnosis. Since the majority of lung cancer patients have an advanced stage at diagnosis, a cytological specimen is frequently the only material available for diagnosis and further prognostic/predictive marker determination. Several types of specimens can be obtained from the respiratory system (including sputum, bronchoalveolar lavage, bronchial brushing, fine needle aspiration, and pleural fluid) with different technical preclinical management protocols and different diagnostic yields. Immunocytochemistry (ICC) has a pivotal role in the determination of diagnostic, prognostic, and predictive markers. Therefore, limited cytology samples are to be used with a cell-sparing approach, to allow both diagnostic ICC evaluation as well as predictive marker assessment by ICC or specific molecular assays. In this review, we describe the most common ICC markers used for the diagnosis and prognostic/predictive characterization of thoracic tumors in different cytological specimens.

The utility of bronchial brushings in the modern era of flexible bronchoscopy

INTRODUCTION

Bronchoscopic procedures allow for the procurement of cellular material for diagnosis, molecular studies, and staging. Procurement modalities include bronchoalveolar lavage (BAL), bronchial washing (BW), transbronchial ultrasound-guided needle aspiration (TBNA), transbronchial biopsy (TBBX), endobronchial biopsy (EB), and bronchoscopic brushing (BB). These specimens, taken concurrently, often circumvent the need for an open biopsy, and allow for more appropriate and efficient patient management. Although BB is a well-established method for obtaining cytologic material, it often introduces artifacts and may contain abundant material such as benign and/or metaplastic bronchial epithelium, both of which may result in atypical or false-positive diagnoses. We examined the utility of BB specimens at our institution in recent years.

METHODS

210 BB specimens were identified at our institution over a 2-year period, allowing for at least a 2-year follow-up period. The diagnoses were compiled and compared against results from simultaneously obtained BAL, BW, TBNA, TBBX, and EB specimens, as well as any follow-up during the subsequent 2- to 4-year period.

RESULTS

BB specimens were diagnosed as malignant (n = 44), benign (130), indeterminate (30), and non-diagnostic (6). There were no false-positive diagnoses. There were 6 instances in which malignancy was not definitively diagnosed on a non-BB specimen but definitively diagnosed on BB.

CONCLUSION

BB specimens rarely provide the only diagnostic material during a bronchoscopic procedure, though they possess excellent specificity for malignancy. Indeterminate diagnoses have a positive predictive value of approximately 73%.