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  MTE22 - A Practical Approach to the Incidental Pulmonary Nodule (ID 66)

  • Event: WCLC 2013
  • Type: Meet the Expert (ticketed session)
  • Track: Pulmonology + Endoscopy/Pulmonary
  • Presentations: 1
  • Moderators:N. n/a
  • Coordinates: 10/30/2013, 07:00 - 08:00, Bayside 105, Level 1

  • 12350

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    MTE22.1 - A Practical Approach to the Incidental Pulmonary Nodule (ID 619)

    07:00 - 07:30  |  Author(s): D. Milne
    • Abstract
    • Presentation
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    Abstract
    A Practical Approach to the Incidental Pulmonary Nodule David Midthun, M.D. David Milne, M.D. The finding of a pulmonary nodule (or multiple nodules) on an imaging study presents a decision point for the patient and physician. In the absence of a completely sensitive and specific non-invasive test for malignancy, the physician and patient must weigh the options for management. The vast majority of such nodules are benign; however the detection of a nodule may be the first and only point in time of a chance of cure in the patient with lung cancer. Guidelines for nodule evaluation by the American college of Chest physicians (ACCP) and the Fleischner Society may help guide the decision making. Studies of lung cancer screening have shown high rates of nodule detection and that the rate is related to the CT slice thickness (collimation) used. Screening with 10 mm collimation results in detection of one or more nodules in approximately 20-25% of participants, 5 mm collimation increases this to 40-50% of participants, and 1.25 mm collimation raises detection to as high as 60%. A review of the data from 8 CT studies in high risk patients (current or former smokers, age 50 or above) reported that likelihood of malignancy was 0 to 1% for nodules < 5 mm, 6 to 28% for nodules 5 to 10 mm, 33 to 60% for nodules > 11-20 mm, and 64 to 82% for nodules > 20-30 mm. The finding of a nodule on CT should first prompt review of any available old images that might include the nodule for comparison. Review of old images may show that the nodule is growing or, alternatively, establish that it has been stable for 2 or more years. Stability in size over a two-year period has been established as an excellent indicator of benignancy for a solid nodule. If old images are not available, nodules < 8 mm may be observed with follow-up CT at an interval determined by the nodule size. Evidence for nodule growth is a hallmark of malignancy and should lead to a staging PET-CT scan (in those who are candidates for surgery) and consideration of prompt resection. Calcification in a benign pattern is an excellent indicator that a nodule is a granuloma and needs no further pursuit. Eccentric calcification should maintain concern for malignancy. Ground-glass nodules (GGN) are nodules of low density (attenuation) that are generally only visible by CT scan. They deserve special mention as they may represent low-grade adenocarcinomas which behave differently than most malignancies presenting as solid nodules. Malignant GGNs typically exhibit slow growth with doubling times on average over 400 days and, for this reason, the 2-year stability rule for solid nodules doesn’t apply and a longer period of follow-up is needed. PET scanning is not helpful to distinguish malignancy due to the low density of the lesions, and needle biopsy is often nondiagnostic. GGNs may show growth or stay the same size yet develop a solid component in the process of progression. PET scanning uses the injection of the glucose analog 18F-2-fluorodeoxyglucose (FDG) and identifies elevated metabolic activity. Nodule enhancement is an indication that a nodule is more likely malignant than benign, and absence of enhancement is a strong predictor that a nodule is benign. In a multicenter prospective study reported that FDG-PET had an overall sensitivity of 92% and a specificity of 90% for detecting malignant nodules, yet the sensitivity fell to only 80% when nodules of 15 mm or smaller were analyzed. A meta-analysis of pulmonary nodules showed that PET had a sensitivity of 94% and a specificity of 86%. The lower limit of solid nodule size for PET applicability using current techniques is about 8-10 mm. A growing nodule that shows no enhancement on PET should still be considered suspicious for malignancy and prompt needle biopsy or resection. If multiple nodules are present, then evaluation is dictated by the largest nodule. Observation may be appropriate for patients with nodules that are larger than 8-10 mm and have a low likelihood of malignancy based lack of enhancement. Whether or not an indeterminate nodule > 8-10 mm should be biopsied is the subject of considerable debate and practices vary. The two biopsy techniques for assessment of nodules are bronchoscopy and transthoracic needle aspiration (TTNA). Bronchoscopy with fluoroscopy alone has a yield of less than 20% in the setting of malignant nodules less than 2 centimeters and in the range of 40-60% when the nodule is 3-4 cm. Studies of guided bronchoscopy using endobronchial ultrasound and/or electromagnetic guidance have shown marked improvements in diagnostic yield over standard fluoroscopic guidance. Studies using one or more of these techniques have shown yields of 60 to 80% of peripheral nodules of a mean diameter of 2- to 25 mm. Yields remain highest with TTNA; multiple studies report yields of 90% and above for nodules < 2 cm and 95% for nodules > 2 cm. Pneumothorax is the most frequent complication of TTNA. Likelihood of obtaining a specific diagnosis in the setting of a benign lesion is problematic for both bronchoscopy and TTNA. Decision as to the method of biopsy involves lesion size, location, presence of a bronchus leading to the lesion, and comorbidities. Preoperative diagnosis may not be needed for lesions that show growth or are nearing 3cm and are PET avid due to the high likelihood of malignancy and low likelihood a biopsy is going to provide a specific benign diagnosis. An exception would be in countries where there is a high prevalence of tuberculosis where sampling may remain appropriate. Resection is the ultimate management for many lesions that remain indeterminate after imaging evaluation especially in a high risk individual. There are currently too many benign nodules removed surgically. Series of video assisted thoracic surgery (VATS) have reported benign nodules representing as high as 50-86% of nodules resected. Reduction in benign nodule resections may be achieved by observing smaller nodules, by utilizing PET-CT, and by performing biopsy by TTNA or bronchoscopy when information is discordant.

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