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The radiographic finding of a pulmonary nodule, formerly known as a coin lesion, has long challenged the clinician. At the heart of the dilemma, the question remains unchanged: “Is it malignant or benign?” When faced with a pulmonary nodule, the clinician and the patient usually have one of three choices: (1) observe it with serial chest computed tomography (CT), (2) perform additional diagnostic tests, or (3) remove it surgically.
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The proper choice depends on epidemiology, radiographic appearance, assessment of surgical risk, and patient preferences. For malignant lesions, early surgical resection still represents the best chance for cure. On the other hand, unnecessary resection of benign nodules exposes patients to the morbidity and mortality of a surgical procedure. The aim of this chapter is to review what is known about the pulmonary nodule to formulate a diagnostic approach to this often controversial problem. The goal will be to arrive at a systematic approach that will promptly identify and bring to surgery all patients with operable malignant nodules while avoiding thoracotomy in patients with benign nodules. To do this, we need to have a clear definition of pulmonary nodules, information on their incidence and prevalence, the causes of malignant and benign nodules, the available imaging techniques, a method of estimating the probability of cancer, the strengths and weakness of serial CT imaging versus different biopsy techniques, and the impact of surgical risk and comorbidities on diagnostic strategies. These various considerations can then be integrated into an algorithm providing a unified approach to diagnosis and management.
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Pulmonary nodules should be characterized on the basis of number, size, and density as determined by CT. A solitary pulmonary nodule is defined as a single discrete pulmonary opacity that is surrounded by normal lung tissue that is not associated with adenopathy or atelectasis.1,2 Previously there was controversy as to what constituted the upper size limit for defining a solitary pulmonary nodule. Some early series included lesions up to 6 cm in size.3,4 However, it is now recognized that lesions larger than 3 cm are almost always malignant, so current convention is that solitary pulmonary nodules must be 3 cm or less in diameter.5–7 Larger lesions should be referred to as pulmonary masses and should be managed with the understanding that they are most likely malignant; prompt diagnosis and resection is usually advisable.7
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The term solitary pulmonary nodule was originally used when most nodules were detected incidentally by chest radiography. Today, most nodules are detected by CT, which greatly enhances nodule detection and characterization. However, we now recognize that many nodules that would have been characterized previously as “solitary” by chest radiograph are actually not solitary, since there may be other small nodules present. Thus, the classic definition of pulmonary nodules needs to be revised to take into account data from more recent CT-based ...