Hazards of Transthoracic Needle Biopsy of the Lung Glen A. Lillington, MD Division of Pulmonary-Critical Care Medicine, Department of Internal Medicine, University of California, Davis, Sacramento, California
espite the widespread employment of transthoracic needle aspiration biopsy of the lung, thoracic surgeons and pulmonologists remain concerned about the frequency and degree of seriousness of the various complications of this valuable diagnostic tool. Pneumothorax occurs in 25% of biopsies, but this is easily recognized and managed. The mortality of the procedure is probably less than 0.1%, with no deaths at all reported in most series, large or small. Lalli and associates [l]reported two deaths in 1,296 biopsies, one of which was a suicide! Deaths are usually due to air embolism, either venous or arterial . Undoubtedly there have been unreported deaths. Implantation of tumor along the needle track is extremely rare with the use of the standard thin needles. The report by Seyfer and colleagues  in this issue is the fourth well-documented case [ P 6 ] of needle track implantation in the lung or chest wall after thin-needle biopsy. Even if we assume that there are probably some unreported cases, the frequency of this complication is clearly very low. Animal experiments cited by Seyfer and associates show a high incidence of malignant cells in the needle track after biopsy. Why then is the appearance of postbiopsy chest wall metastases so rare in humans? A partial explanation may lie in the fact that, in the past, the majority of needle aspirations for malignant tumors were carried out to confirm the diagnosis in cases that were clearly inoperable. Many of these patients were then given radiation therapy, which probably sterilized microscopic implants, and others with advanced disease presumably died of systemic tumor metastases before tumor implants from the needle biopsy had time to become clinically apparent. In most cases, it would appear that the tumor cells in the needle track fail to form metastatic deposits. Such hazards, although real, must be considered in the context of the advantages of performing the biopsy. As many solitary nodules are benign, needle biopsy offers a reasonable chance of establishing benignity so that exploratory thoracotomy, with its small but definite mortality, may be obviated. These competing risks can be compared more accurately by including the likelihood of benignity and the ability of the needle biopsy to reliably define benign lesions in the decision process. In an analysis of the optimal management of solitary pulmonary nodules , the strategy of immediate thoraAddress reprint requests to Dr Lillington, Division of Pulmonary-Critical Care Medicine, University of California, Davis, 4301 X St, Sacramento, CA 95817.
1989 by The Society of Thoracic Surgeons
cotomy was compared with the strategy of initial needle biopsy, expressed in terms of average years of life expectancy. Immediate thoracotomy for solitary uncalcified pulmonary nodules of unknown stability conferred a slightly greater average life expectancy than the biopsy strategy if the projected probability that the nodule was malignant was greater than 70%, whereas the strategy of initial needle biopsy was marginally preferable to immediate thoracotomy if the probability that the nodule was malignant was less than 70%. The clinical variables employed in the calculation of the probability of malignancy in a nodule included the age of the patient, the smoking history, and nodule diameter . As would be expected, the advantage for needle biopsy as the preliminary procedure becomes somewhat greater if the predicted surgical mortality for exploratory thoracotomy is unduly high. With "standard" mortality rates (4% for resection of malignant nodules, 0.5% for removal of benign nodules), the differences in outcome, in terms of average life expectancy, between the needle biopsy and thoracotomy strategies are relatively miniscule over a wide range of values for the probability of malignancy. In such situations, the desires of the patient may properly become paramount in management decisions. Some patients are "risk-averse" and prefer to avoid thoracotomy unless a diagnosis of malignancy has been established; needle aspiration as the initial procedure would usually be chosen in this circumstance. Conversely, patients who prefer to get the problem settled definitively and expeditiously would undoubtedly choose exploratory thoracotomy as the initial investigative procedure. As the two strategies are approximately equal in terms of average life expectancy, either choice is reasonable and appropriate. I have recalculated the expected values for the needle biopsy strategy after modifying the decision tree to allow for the possibility of chest wall metastasis by needle track implantation, assuming an incidence of one such event in each thousand biopsies and a life expectancy after biopsy of only 1 year if implantation occurred. The average life expectancy of the needle biopsy strategy dropped, but only by a trivial amount. This is supportive of the clinical perception that tumor implantation after needle biopsy of the lung is a remote eventuality that need not carry major weight in the decision process.
References 1. Lalli AF, McCormack LJ, Zelch M, et al. Aspiration biopsies of chest lesions. Radiology 1978;127:3540. Ann Thorac Surg 1989;48:163-4
EDITORIAL LILLINGTON HAZARDS OF TRANSTHORACIC NEEDLE LUNG BIOPSY
Aberle DR, Gamsu G, Golden JA. Fatal systemic arterial air embolism following lung needle aspiration. Radiology 1987; 165:351-3. Seyfer AE, Walsh DS, Graeber GM, Nuno IN, Eliasson AH. Chest wall implantation of lung cancer after thin-needle aspiration biopsy. Ann Thorac Surg 1989;48:28&6. Sinner WN, Zajicek J. Implantation metastasis after percutaneous needle aspiration biopsy. Acta Radio1 Diagn 1976;17: 47HO. Moloo Z , Finley R, Lefcoe M, et al. Possible spread of
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bronchogenic carcinoma to the chest wall after a transthoracic fine-needle aspiration biopsy. Acta Cytol 1985;29:167-9. 6. Muller N, Bergin C, Miller R, Ostrow D. Seeding of malignant cells into the needle tract after lung and pleural biopsy. J Can 1986;37:1924' 7. Cummings SR, Lillington GA, Richard RJ. Managing solitary pulmonary nodules: the choice of strategy is a "close call." Am Rev Respir Dis 1986;134:453-60, 8, cummings SR, ~ i l l GA, i ~Richard ~ ~ RJ. ~ ~ ~the probability of malignancy in solitary pulmonary nodules: a Bayesian approach. Am Rev Respir Dis 1986;135:449-52.