Solitary pulmonary nodule - Causes and Symptoms

Related articles: Solitary pulmonary nodule

Definition

A solitary pulmonary nodule is an isolated lung lesion, less than 3 cm in diameter, completely surrounded by pulmonary parenchyma (not in contact with the hilum, mediastinum or pleura) and not associated with other anomalies.

Solitary pulmonary nodules are often found accidentally due to chest x-rays or CT scans performed for other reasons.

Although most solitary pulmonary nodules are benign, the possibility exists that the lesion is malignant. The risk is more consistent in the elderly and smokers.

In addition to bronchogenic carcinoma, the differential diagnosis includes other primary lung cancers (such as small cell carcinoma and adenocarcinoma) and metastases from the colon, breast, prostate, thyroid, kidneys, testicles, melanomas and sarcomas.

The most common benign cause is granuloma, which often represents the outcome of a previous infection with endemic fungi or mycobacteria (TB, coccidioidomycosis, histoplasmosis, blastomycosis, cryptococcosis and nocardiosis). A solitary pulmonary nodule can also result from chronic inflammation, progressive pulmonary fibrosis, benign neoplasms such as hamartomas, fibroids and lipomas. In other cases, the lesion depends on bacterial abscesses and infectious diseases such as pneumonia and echinococcosis. A solitary pulmonary nodule can also represent an inflammatory lesion as in the case of Wegener's granulomatosis or rheumatoid nodules.

Other etiologies include: bronchogenic cysts, amyloidosis, intrapulmonary lymph node, hematoma, mucosal inclusion, foreign body and pulmonary vascular anomalies (arteriovenous malformation, spider veins, hemangioma and cavernous angioma).