Solitary Pulmonary Nodule
80 SOLITARY PULMONARY NODULE
Jamie M. Brown M.D., Marvin Pomerantz M.D.
1. What is a solitary pulmonary nodule?
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A solitary pulmonary nodule or “coin lesion” is < 3 cm and is discrete on chest radiograph. It is usually surrounded by lung parenchyma.
2. What causes a solitary pulmonary nodule?
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The most common causes of a pulmonary nodule are either neoplastic (carcinoma) or infectious (granuloma). Pulmonary nodules may also represent lung abscess, pulmonary infarction, arteriovenous malformations, resolving pneumonia, pulmonary sequestration, hamartoma, and others. As a general rule of thumb, likelihood of malignancy is proportionate to the patient’s age. Thus, whereas lung cancer is rare (although it does occur) in 30-year-old individuals, in 50-year-old smokers, the chances of malignancy may be as high as 50-60%.
3. How does a solitary pulmonary nodule present?
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Typically, a solitary nodule is picked up incidentally on routine chest radiograph. In several large series, more than 75% of lesions were surprise findings on routine chest radiograph. Fewer than 25% of patients had symptoms referable to the lung. Solitary nodules are now seen on other sensitive imaging tests such as helical computed tomography (CT).
4. How frequently does a solitary pulmonary nodule represent metastatic disease?
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Fewer than 10% of solitary nodules represent metastatic disease. Accordingly, an extensive workup for a primary site of cancer other than the lung is not indicated.
5. Can a tissue sample be obtained by fluoroscopic or CT-guided needle biopsy?
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Yes, but the results do not change the treatment. If the needle biopsy tissue indicates cancer, the nodule must be removed. If the needle biopsy is negative for cancer, the nodule must still be removed. Positron emission tomography (PET) is 90% sensitive in identifying malignant tumors.
6. Are radiographic findings important?
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Only relatively. The resolution of modern CT scanners allows the best identification of characteristics that suggest cancer:
1. Indistinct or irregular spiculated borders of the nodule.
2. The larger the nodule, the more likely it is to be malignant.
3. Calcification in the nodule generally is associated with benign disease (the opposite of breast cancer). Specifically, whereas central, diffuse, or laminated calcifications are typical of a granuloma, calcifications with more dense and irregular “popcorn” patterns are associated with hamartomas. Unfortunately, eccentric foci of calcium or small flecks of calcium may be found in malignant lesions.
4. Nodules can be studied using a CT scanner by measuring their change in relative radiodensity after injection of contrast. This information improves the accuracy of predicting the presence of malignancy.
KEY POINTS: SOLITARY PULMONARY NODULE
1. A solitary pulmonary nodule or “coin lesion” is < 3 cm and is discrete on chest radiograph.
2. The most common causes of a pulmonary nodule are either neoplastic or infectious.
3. If the lesion proves to be cancer, anatomic lobectomy is the procedure of choice.
7. What social or clinical findings suggest that a nodule is malignant rather than benign?
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Unfortunately, none of the findings is sufficiently sensitive or specific to influence the work-up. Both increasing age and a long smoking history predispose patients to lung cancer. Winston Churchill should have had lung cancer, but he did not. Thus, the fact that the patient is the president of the spelunking club (histoplasmosis), has a sister who raises pigeons (cryptococcosis), grew up in the Ohio River Valley (histoplasmosis), works as sexton for a dog cemetery (blastomycosis), or just took a hiking trip through the San Joaquin Valley (coccidioidomycosis) is interesting associated history but does not affect the work-up of a solitary pulmonary nodule.
8. What is the most valuable bit of historic data?
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The most valuable is an old chest radiograph. If the nodule is new, it is more likely to be malignant, whereas if the nodule has not changed in the past 2 years, it is less likely to be malignant. Unfortunately, even this observation is not absolute.
9. If a patient presents with a treated prior malignancy and a new solitary pulmonary nodule, is it safe to assume that the new nodule represents metastatic disease?
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No. Even in patients with known prior malignancies, < 50% of new pulmonary nodules are metastatic. Thus, the work-up should proceed exactly as for any other patient with a new solitary pulmonary nodule.
10. How should a solitary pulmonary nodule be evaluated?
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A complete travel and occupational history is interesting but does not affect the evaluation. Because of the peripheral location of most nodules, bronchoscopy has a diagnostic yield of < 50%. Even in the best hands, sputum cytology has a low yield. CT scanning is recommended because it can identify other potentially metastatic nodules and delineate the status of mediastinal lymph nodes. As indicated previously, percutaneous needle biopsy has a diagnostic yield of approximately 80% but rarely alters the subsequent management. PET scanning may suggest cancer with accuracy.
The mainstay of management in patients who can tolerate surgery is resection of the nodule, usually by lobectomy if cancer is suspected, for diagnosis by either a minimally invasive thoracoscopy approach or a limited thoracotomy.
11. If the lesion proves to be cancer, what is the appropriate surgical therapy?
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Although several series have suggested that wedge excision of the nodule is sufficient, an anatomic lobectomy remains the procedure of choice. This can often be accomplished by a video-assisted approach. A solitary nodule that turns out to be cancer should be early-stage disease and has a 65% 5-year survival rate if there are no notable metastases. Unfortunately, the recurrence rate even for stage I tumors or a small nodule is 30% over 5 years. Recurrences are split between local and distant.
References
WEB SITE
http://www.acssurgery.com
BIBLIOGRAPHY
1. Dewey TM, Mack MJ: Lung cancer: Surgical approaches and incisions. Chest Surg Clin North Am 10:803-820, 2000.
2. Ginsberg RJ, Rubinstein LV: Randomized trial of lobectomy versus limited resection for T1 N0 non-small cell lung cancer. Lung Cancer Study Group. Ann Thorac Surg 60:615-622, 1995. Medline Similar articles Full article
3. Khouri NF, Meziane MA, Zerhouni EA, et al: The solitary pulmonary nodule: Assessment, diagnosis and management. Chest 91:128-133, 1987. Medline Similar articles
4. Miller DL, Rowland CM, Deschamps C, et al: Surgical treatment of non-small cell lung cancer 1 cm or less in diameter. Ann Thorac Surg 73:1541-1545, 2002.
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Abernathy’s Surgical Secrets, Updated Edition (Book w / Student Consult)
Author / s: Harken Alden H., Abernathy Charles, Moore Ernest Eugene
Year: 2004
Pages: 473
Publishers: Elsevier Mosby; 5th Bk & Acc edition
ISBN: 0323034160
