Management Recommendations
Lesions that have typical benign features, such as lack of change over two years or a benign pattern of calcification, especially in low-risk patients, do not require further workup. On the other hand, lesions that are strongly suggestive of malignancy (eg. > 3 cm diameter) or those with documented growth should be referred for surgical resection. [48]
Management decisions for lesions with intermediate probability (which is the case for most lesions) are more complex. Although management varies amongst individual institutions and practitioners, several guidelines have been published.
Fleischner Society recommendations
In 2017, [49] the Fleischner Society updated its 2005 guidelines [50] for the management of incidentally found solitary pulmonary nodules (SPNs). New data from many international trials [51, 52, 53] were incorporated into the guidelines to facilitate more patient preference and clinician judgement. These recommendations are not applicable to lung cancer screening CT findings and were intended for individuals who are aged at least 35 years, immunocompetent, and without known primary cancers.
The major determinants of these guidelines are size and characteristics of the nodule(s), along with risk factors. As per the guidelines, high-risk features are as follows:
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Age older than 40 years
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Female sex
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Family history of lung cancer
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Black male or native Hawaiian male
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Upper lobe location
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Spiculation of the nodule
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Radiographic emphysema
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Presence of pulmonary fibrosis, particularly idiopathic pulmonary fibrosis (IPF)
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Thirty or more pack-year history of tobacco smoking and currently active or cessation within the past 15 years [51]
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Exposure to asbestos, uranium, or radon
According to the guidelines, follow-up imaging for patients with a single, solid, noncalcified nodule should occur as follows:
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Less than 6 mm - No routine follow up; if high-risk, an optional CT scan can be considered in 12 months; this CT scan may be warranted based on suspicious morphology and/or upper lobe location of the nodule
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From 6-8 mm - CT scan at 6-12 months, followed by consideration for a repeat CT scan at 18-24 months but, if high-risk, then proceed with a repeat CT scan at 18-24 months
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Greater than 8 mm - Consider PET-CT, CT scan at 3 months, biopsy, or a combination of tests
The guidelines recommend that follow-up imaging for more than one solid, noncalcified nodule should be determined by the most suspicious-appearing nodules and should occur as follows:
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Less than 6 mm - No routine follow up; if high-risk, an optional CT scan can be considered in 12 months, which may be warranted based on suspicious morphology and/or upper lobe location of the nodule
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Greater than 6 mm - CT scan at 3-6 months, followed by consideration for repeat CT scan at 18-24 months, but if high-risk, then repeat CT scan at 18-24 months
If a single ground-glass nodule is found, then the recommendations are follows:
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Less than 6 mm - No further routine follow up
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Six mm or greater - CT scan at 6-12 months, and if the nodule persists, then repeat CT scan every 2 years to complete a 5-year period
For a single, part-solid nodule recommendations are as follows:
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Less than 6 mm - No further routine follow up
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Six mm or greater - CT scan at 3-6 months, and if the nodule persists with the solid component less than 6mm, perform a CT scan annually for 5 years; if the solid component is 6 mm or larger with suspicious features (eg, solid component growth , lobulated margins), then PET-CT, surgical resection, or biopsy is recommended
If multiple subsolid (ie, ground-glass and/or part-solid) nodules are found, the recommendations are based on the most suspicious-appearing nodule, as follows:
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Less than 6 mm - CT scan in 3-6 months and if they remain stable, follow up CT scan at the 2- and 4-year mark
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Six mm or greater - CT scan in 3-6 months, followed by further management determined by the most suspicious-appearing nodule
American College of Chest Physicians (ACCP) recommendations
The most recent edition of the ACCP guidelines for the management of solitary pulmonary nodules were published in 2013. [54] Specifically, indeterminate nodules, found via any imaging modality, were addressed. They were defined as any nodule without clearly benign features (eg, intranodular fat indicative of hamartoma) or noncalcified in a benign pattern. The upper limit for the number of nodules was arbitrarily chosen as 10. The guidelines can be summarized as follows:
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Carefully calculate pretest probability for malignancy, either through experienced clinical judgment or through a validated model (see Assessing the Probability of Malignancy, above)
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Previous chest imaging should be reviewed and chest CT scan should be performed if the indeterminate nodule was noted on chest radiograph
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If the lesion is solid and has been stable for at least 2 years, no further follow up is necessary
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For lesions with a benign pattern of calcification, further testing is not necessary
Management of indeterminate solid lesions greater than 8-30 mm depends on first determining the pretest probability of malignancy and thereafter, if the following is noted:
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Very low probability (< 5%) - Serial CT scanning at 3-6 months, 9-12 months, and then at 18-24 months
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Low-to-moderate probability (5%-65%) - PET imaging; if uptake is minimal, CT surveillance or nonsurgical biopsy, but if moderate or intense uptake, either nonsurgical biopsy or surgical resection
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High probability (>65%) - Surgical resection, ideally thoracoscopic wedge resection; those at high risk for surgical complications
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Any unequivocal growth noted during follow up CT scans - Definitive tissue diagnosis with nonsurgical biopsy and/or surgical resection
Tumor Resection
When a lesion is likely to be malignant, surgical resection, not TTNA or observation, is often used. The purpose of surgical intervention for benign lung tumors is to avoid missing potentially malignant lesions. Otherwise, benign lung tumors should be removed when they are symptomatic. The existence of symptoms indicates that complications such as pneumonia, atelectasis, and/or hemoptysis are present.
After discussion of the potential surgical and nonsurgical options, those deemed unable to tolerate a surgical approach or who prefer a nonsurgical approach can consider other therapies. Options include stereotactic body radiation therapy (SBRT), radiofrequency ablation (RFA), and other modalities that use microwave-targeted treatment and cryoprobes.
Types of procedures
The extent of surgery may be simple endoscopic resection, thoracotomy with bronchotomy/local excision, segmental resection, lobectomy, sleeve resection, or pneumonectomy. The extent of the procedure is usually determined at surgery and is as conservative as possible.
Advances in minimally invasive techniques have made it less important to avoid removing lesions that may be benign. No longer must a patient be subjected to a large incision (posterolateral thoracotomy) for the purpose of diagnosing a solitary pulmonary nodule or treating a benign lung tumor. Moreover, localized resection (wedge resection) performed with a minimally invasive technique has decreased the length of hospital stay and morbidity for patients with benign lung tumors.
Commonly, surgical resection is recommended for bronchial adenomas because of the potential for malignancy. The surgical approach should include complete resection, sparing of as much lung as possible, and lymph node dissection. Endoscopic resection using a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser can be used for adenomas in high-risk or elderly patients.
Operative considerations
Anesthetic preparation is similar to that for any standard thoracotomy and involves the use of an epidural, a double-lumen endotracheal tube, and invasive lines (including a radial artery catheter and a central line). Prior to double-lumen placement, bronchoscopy via a standard endotracheal tube should identify any endobronchial component and plan for the surgical resection.
The 2013 ACCP guidelines recommend that patients who have indeterminate lung nodules with a high probability of malignancy undergo thoracoscopic wedge resection of the nodule. This is because of the relatively low morbidity and mortality associated with the procedure, compared with open thoracotomy. [55] If frozen sections show evidence of malignancy, anatomic resection with mediastinal lymph node sampling or dissection may be performed.
Localization during thoracoscopy using methylene blue injection, radioguidance, or hook-and-wire placement has facilitated successful resection of smaller (< 1 cm) nodules. Intraoperative ultrasonography is also suggested as a means of nodule localization during this type of operation. [56]
At the time of open thoracotomy, perform a complete tumor resection and conserve as much lung as possible. In the setting of a lung adenoma, a complete lymph node dissection should also be performed.
For a proven malignant solitary pulmonary nodule, lobectomy is preferred over wedge resection or segmentectomy because of the lower rate of recurrence and a trend toward increased 5-year survival with lobectomy. [57]
Prevention
Avoiding certain occupational, recreational, and environmental respiratory exposures may help to prevent solitary pulmonary nodule formation. This includes avoidance of risk factors for malignancy, which include smoking and occupational exposures (eg, asbestos, radon, nickel, chromium, vinyl chloride, polycyclic hydrocarbons).
Avoidance of travel to areas endemic for mycosis (eg, histoplasmosis, coccidioidomycosis, blastomycosis) or to areas with a high prevalence of tuberculosis can also help to prevent the development of these nodules.
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Right upper lobe nodule shows peripheral calcification and high Hounsfield unit enhancement, suggesting that the lesion is a calcified, benign pulmonary nodule.
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A 1.5-cm coin lesion in the left upper lobe in a patient with prior colonic carcinoma. Transthoracic needle biopsy findings confirmed this to be a metastatic deposit.
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Mediastinal windows of the patient in the previous image
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Right lower lobe nodule demonstrating central calcification. The most likely diagnosis is histoplasmosis.
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Close-up view of a right lower lobe nodule demonstrating central calcification. The most likely diagnosis is histoplasmosis.
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Left upper lobe cavitating solitary nodule eventually identified as active pulmonary tuberculosis from percutaneous needle biopsy findings.
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A left upper lobe nodule with central lucency and poorly circumscribed margins was diagnosed as actinomycosis based on needle biopsy findings.
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Computed tomography (CT) scan of the patient in the previous image. After needle biopsy, the presence of classic sulfur granules confirmed a diagnosis of actinomycosis.
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A right lower lobe solitary pulmonary nodule that was later identified as a hamartoma.
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Wedge-shaped peripheral (pleural based) density observed secondary to pulmonary infarction (pulmonary embolism). This is termed the Hampton hump.
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Left upper lobe 1.5-cm nodule shows negative computed tomography (CT) scan numbers, suggesting fat in the lesion consistent with hamartoma.
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A left upper lobe solitary pulmonary nodule. The differential diagnosis in such cases is large, but computed tomography (CT) scan findings help to narrow the differentials and establish the diagnosis.
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Cavitating right lower lobe nodule later confirmed to be primary pulmonary lymphoma. Calcium deposits may also be present in the lesion.
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This left lower lobe carcinoid tumor was quite bloody after a percutaneous needle biopsy was performed.
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Lateral radiograph of the patient in the previous image.
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Computed tomography (CT) scan of a patient with a left lower lobe carcinoid tumor shows a well-circumscribed lesion.
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A popcorn calcification in the left lung nodule indicates a benign lesion or hamartoma. No further tests or observations were needed for this patient.
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A 1.5-cm right upper lobe nodule on a computed tomography (CT) scan was determined to be a benign, fibrous lesion on needle biopsy. A follow-up at 2 years showed no change in the size of this lesion.
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The parenchymal lesion in this computed tomography (CT) scan demonstrates low attenuation within the lesion, indicating the presence of fat. Fat density is observed only in hamartoma and lipoid pneumonia. The likely diagnosis is hamartoma
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This patient has a low risk for malignancy of the right upper lobe nodule. Therefore, continued observation with repeat chest radiographs to establish a growth pattern is the best treatment option.
