eMedicine Specialties > Pulmonology > Lung Tumors

Solitary Pulmonary Nodule

Author: Sat Sharma, MD, FRCPC, Professor and Head, Division of Pulmonary Medicine, Department of Internal Medicine, University of Manitoba; Site Director, Respiratory Medicine, St. Boniface General Hospital
Coauthor(s): Sri R Navaratnam, MBBS, PhD, FRCPC, Assistant Professor, Department of Internal Medicine, Section of Hematology/Oncology, University of Manitoba; Consulting Medical Oncologist, Department of Hematology/Oncology, Cancer Care Manitoba
Contributor Information and Disclosures

Updated: Jun 14, 2006

Introduction

Background

Patients with solitary pulmonary nodules (SPNs) are usually asymptomatic; however, SPNs pose a challenge to both physicians and patients. Whether detected serendipitously or during a routine investigation, a nodule on a chest radiograph raises several questions: Is the nodule benign or malignant? Should it be investigated or observed? Should it be surgically resected?

Most SPNs are benign, but they may represent an early stage of lung cancer. Lung cancer is the leading cause of cancer death in the United States, accounting for more deaths annually than breast, colon, and prostate cancers combined. Lung cancer survival rates remain dismally low at 14% at 5 years. Early lung cancer, when the primary tumor is less than 3 cm in diameter (stage 1A), may lead to 5-year survival rates of 70-80%. Therefore, prompt diagnosis and management of early lung cancer manifesting as SPN may be the only chance for cure.

Pathophysiology

An SPN is defined as a single, discrete pulmonary opacity that is less than 3 cm in diameter, surrounded by normal lung tissue, and not associated with adenopathy or atelectasis.

Generally, a pulmonary nodule must reach 1 cm in diameter before it can be identified on a chest radiograph. For a malignant nodule to reach this size, approximately 30 doublings would have occurred. The average doubling time for a tumor is 120 days (range, 7-590 d). A lesion at this growth rate may be present for 10 years before discovery.

An SPN may be secondary to one of the numerous differential diagnoses listed in Causes. However, more than 95% are neoplasms (most likely primary), granulomas (most likely infectious), or benign lesions (most likely hamartoma).

Frequency

United States

SPNs are one of the most common thoracic radiographic abnormalities. Approximately 150,000 cases are detected each year as an incidental finding, either on images from chest radiographs or images from thoracic CT scans (Lillington, 1991). Approximately 40-50% of these nodules are malignant. Most are bronchogenic carcinoma, but 10-30% may be solitary metastases.

Mortality/Morbidity

Most SPNs are benign, but they may represent an early stage of lung cancer.

  • While lung cancer survival rates remain dismally low at 14% at 5 years, early lung cancer, ie, diagnosed when the primary tumor has a diameter smaller than 3 cm (stage 1A), can be associated with a 5-year survival rate of 70-80%.
  • Accordingly, the only chance for cure of early lung cancer manifesting as SPN is prompt diagnosis and management.

Age

Risk of malignancy increases with age.

  • For individuals younger than 39 years, the risk is 3%.
  • The risk increases to 15% for individuals aged 40-49 years, to 43% for persons aged 50-59 years, and to more than 50% for persons older than 60 years.

Clinical

History

Patients with solitary pulmonary nodules (SPNs) are asymptomatic; the nodules are typically detected as an incidental finding. Approximately 20-30% of all bronchogenic carcinomas appear as SPNs on initial radiographs. The following features are important when assessing whether the nodule is benign or malignant.

  • History of smoking
  • History of malignancy
  • Travel: Travel to areas with endemic mycosis (eg, histoplasmosis, coccidioidomycosis, blastomycosis) or to areas with a high prevalence of tuberculosis (TB) can lead to the development of a benign SPN.
  • Occupational risk factors for lung cancer: Exposure to asbestos, radon, nickel, chromium, vinyl chloride, and polycyclic hydrocarbons can lead to acquisition of an SPN.
  • History of TB or pulmonary mycosis

Causes

Bearing in mind that the major distinction that must be made is between neoplastic and inflammatory lesions, SPNs may have the following causes:
  • Neoplastic (malignant or benign)
    • Bronchogenic carcinoma
    • Metastasis
    • Lymphoma
    • Carcinoid
    • Hamartoma
    • Connective tissue and neural tumors - Fibroma, neurofibroma, blastoma, sarcoma
  • Inflammatory (infectious)
    • Granuloma - TB, histoplasmosis, coccidioidomycosis, blastomycosis, cryptococcosis, nocardiosis
    • Lung abscess
    • Round pneumonia
    • Hydatid cyst
  • Inflammatory (noninfectious)
    • Rheumatoid arthritis
    • Wegener granulomatosis
    • Sarcoidosis
    • Lipoid pneumonia
  • Congenital
    • Arteriovenous malformation
    • Sequestration
    • Lung cyst
  • Miscellaneous
    • Pulmonary infarct
    • Round atelectasis
    • Mucoid impaction
    • Progressive massive fibrosis

More on Solitary Pulmonary Nodule

Overview: Solitary Pulmonary Nodule
Differential Diagnoses & Workup: Solitary Pulmonary Nodule
Treatment & Medication: Solitary Pulmonary Nodule
Follow-up: Solitary Pulmonary Nodule
Multimedia: Solitary Pulmonary Nodule
References

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Further Reading

Keywords

solitary pulmonary nodule, SPN, early lung cancer, histoplasmosis, coccidioidomycosis, blastomycosis, pulmonary mycosis, tuberculosis, TB, bronchogenic carcinoma, nocardiosis, asbestos exposure, radon exposure, nickel exposure, chromium exposure, vinyl chloride exposure, polycyclic hydrocarbon exposure, chemical exposure, industrial exposure, bronchogenic cancer, bronchogenic malignancy, pulmonary mycosis, mycosis, lung nodule, malignant nodule, lung lesion, lung malignancy, neoplasm, primary neoplasm, lung neoplasm, granuloma, infectious granuloma, lung granuloma, benign lung lesion, hamartoma, lymphoma, carcinoid, fibroma, neurofibroma, blastoma, sarcoma, lung abscess, round pneumonia, hydatid cyst, rheumatoid arthritis, RA, Wegener granulomatosis, sarcoidosis, lipoid pneumonia, arteriovenous malformation, AVM, lung cyst, pulmonary infarct, round atelectasis, mucoid impaction, mucus impaction, progressive massive fibrosis

Contributor Information and Disclosures

Author

Sat Sharma, MD, FRCPC, Professor and Head, Division of Pulmonary Medicine, Department of Internal Medicine, University of Manitoba; Site Director, Respiratory Medicine, St. Boniface General Hospital
Sat Sharma, MD, FRCPC is a member of the following medical societies: American Academy of Sleep Medicine, American College of Chest Physicians, American College of Physicians-American Society of Internal Medicine, American Thoracic Society, Canadian Medical Association, Royal College of Physicians and Surgeons of Canada, Royal Society of Medicine, Society of Critical Care Medicine, and World Medical Association
Disclosure: Nothing to disclose.

Coauthor(s)

Sri R Navaratnam, MBBS, PhD, FRCPC, Assistant Professor, Department of Internal Medicine, Section of Hematology/Oncology, University of Manitoba; Consulting Medical Oncologist, Department of Hematology/Oncology, Cancer Care Manitoba
Disclosure: Nothing to disclose.

Medical Editor

Stephen P Peters, MD, PhD, Professor, Department of Medicine, Wake Forest University
Stephen P Peters, MD, PhD is a member of the following medical societies: American Academy of Allergy Asthma and Immunology, American Association of Immunologists, American College of Chest Physicians, American College of Physicians, American Federation for Medical Research, American Thoracic Society, and Sigma Xi
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Robert S Crausman, MD, MMS, Chief Administrative Officer, Rhode Island Board of Medical Licensure and Discipline, Rhode Island Department of Health; Associate Professor, Department of Medicine, Brown University School of Medicine
Robert S Crausman, MD, MMS is a member of the following medical societies: American College of Chest Physicians and American College of Physicians
Disclosure: Nothing to disclose.

CME Editor

Timothy D Rice, MD, Associate Professor, Departments of Internal Medicine and Pediatrics and Adolescent Medicine, Saint Louis University School of Medicine
Timothy D Rice, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Physicians
Disclosure: Nothing to disclose.

Chief Editor

Zab Mosenifar, MD, Director, Division of Pulmonary and Critical Care Medicine, Director, Women's Guild Pulmonary Disease Institute, Executive Vice Chair, Department of Medicine, Cedars Sinai Medical Center; Professor of Medicine, David Geffen School of Medicine at UCLA
Zab Mosenifar, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Federation for Medical Research, and American Thoracic Society
Disclosure: Nothing to disclose.

 
 
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