Wednesday, March 7, 2012

Pulmonary Nodules

Multiple pulmonary nodules on chest x-ray, known commonly as cannon ball secondaries, are the classical presentation of haematogenous dissemination of a malignant tumor to the lungs. This almost always indicates advanced stage of the disease with a very grim outlook in terms of cure or survival. But there are numerous causes for multiple pulmonary nodules and their interpretation as cannon ball metastases should be viewed with caution. Here we present one such instance of “non-malignant” multiple pulmonary nodules.

-Multiple pulmonary nodules seen on plain chest x-ray have a multitude of causes, starting from metastases (cannon ball secondaries), various infections, immunological diseases to arterio-venous malformations.

-Pulmonary metastases in adults are usually from breast, kidney, gut, testes, head-neck tumors and a variety of sarcomas. The basic sign of haematogenous pulmonary metastases is one or more discrete pulmonary nodules. The nodules are usually spherical and well-defined, but they may be almost of any shape and can occasionally have a very irregular edge, especially in adenocarcinoma

-Calcification is very unusual except in osteo/chondrosarcoma. Secondary deposits can also present as miliary mottling throughout the lung fields or with extensive perihilar spread (lymphangitis carcinomatosa)

-Septicemic infections by Staphylococcus aureus cause disseminated, multifocal, nodular consolidations which can cavitate.This type of infection may be seen in drug addicts, immunocompromised patients, and patients with infective endocarditis or indwelling catheters. Gram-negative pneumonias in hospital setting are commonly caused by enterobacteria, Pseudomonas aeruginosa, and Haemophilus influenzae. These agents are the most common cause of nosocomial pneumonia. Patients affected are invariably debilitated by chronic lung disease, major medical conditions, or surgery. The radiological patterns are similar to those seen with Staphylococcus aureus

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