Solitary Pulmonary Nodule Causes

Solitary pulmonary nodules may have the following causes:

• Neoplastic (an abnormal growth that can be benign or malignant)
  
  
  • Lung cancer
  
  
  
  • Metastasis (spread of cancer from other parts of the body to the lung)
  
  
  
  • Lymphoma (a tumor made up of lymphoid tissue)
  
  
  
  • Carcinoid (a small, slow-growing tumor that can spread)
  
  
  
  • Hamartoma (an abnormal mass of normal tissues that are poorly organized)
  
  
  
  • Fibroma (a tumor made up of fibrous connective tissue)
  
  
  
  • Neurofibroma (a noncancerous tumor made up of nerve fibers)
  
  
  
  • Blastoma (a tumor composed mainly of immature, undifferentiated cells)

• Sarcoma (a tumor made up of connective tissue [usually cancerous])

• Inflammatory (infectious) - Granuloma (small, granular inflammatory lesions)



• Infection caused by bacteria - Tuberculosis



• Infections caused by fungi - Histoplasmosis, coccidioidomycosis, blastomycosis, cryptococcosis, nocardiosis



• Other infectious causes
  
  
  • Lung abscess (an infection in which cells of a part of the lung die)
  
  
  
  • Round pneumonia (infection caused by virus or bacteria; air spaces of the lungs are filled with fluid and cells)
  
  
  
  • Hydatid cyst (a cyst formed by the larval stage of a tapeworm, Echinococcus) 

• Inflammatory (noninfectious)

• Rheumatoid arthritis (a generalized disease of the connective tissues; joint pain is the main symptom)



• Wegener granulomatosis (inflammation of the small blood vessels characterized by lesions that kill the cells in different organs of the body)



• Sarcoidosis (a disease characterized by granular lesions of unknown cause that involves various organs of the body)



• Lipoid (resembling fat) pneumonia

• Congenital

• Arteriovenous malformation (failure of proper or normal development of arteries and veins)



• Sequestration (a piece of lung tissue that has become separated from the surrounding healthy tissue)



• Lung cyst (an abnormal sac that contains gas, fluid, or a semisolid material, with a membranous lining)

• Miscellaneous

• Pulmonary infarct (death of cells or of a portion of lung, resulting from a sudden insufficiency of arterial or venous blood supply)



• Round atelectasis (decreased or absent air in a part of the lung)



• Mucoid impaction (the filling of parts of the lung with mucus)



• Progressive massive fibrosis (formation of fibrous tissue as a reactive process, as opposed to formation of fibrous tissue as a normal constituent of an organ or tissue)



• Occasionally, a shadow on the x-ray film may be mistaken for an SPN.