What does mosaic attenuation mean in medical terms?

Mosaic attenuation refers to the appearance of patchy areas of increased and decreased density on a computed tomography (CT) scan. It is specifically seen in the lung and suggests a variety of conditions, including:

- Infection: Mosaic attenuation can be caused by a variety of infections, including pneumonia, bronchitis, and tuberculosis. In this setting, it is thought to represent areas where the infection has caused inflammation and fluid buildup, alternating with areas of normal lung tissue. Mosaic attenuation can also be seen in viral respiratory infections, such as COVID-19.

- Cryptogenic Organizing Pneumonia (COP): Mosaic attenuation is a common finding in COP, which is a rare lung disease characterized by the formation of plugs of inflammatory tissue in the small airways.

- Aspiration Pneumonia: Mosaic attenuation can be seen in aspiration pneumonia, a type of pneumonia that occurs when foreign material, such as food or drink, is inhaled into the lungs.

- Radiation pneumonitis: This condition is caused by the inflammation of the lung tissue as a result of radiation therapy. Mosaic attenuation can be a feature of radiation pneumonitis, particularly in the acute phase.

- Pulmonary embolism: Mosaic attenuation can be seen in some cases of pulmonary embolism, which is a blockage of the arteries in the lungs by blood clots.

- Bronchiolitis obliterans organizing pneumonia (BOOP): This is a rare lung disease characterized by the formation of plugs of inflammatory tissue in the small airways. Mosaic attenuation is commonly seen in BOOP.

- Lung contusion: Mosaic attenuation can be seen in lung contusion, which is a bruise to the lung tissue caused by blunt force trauma.

- Infiltrative lung diseases: Mosaic attenuation can also be seen in infiltrative lung diseases, such as sarcoidosis and amyloidosis, where there is a buildup of abnormal material in the lung tissue.

- Hypersensitivity pneumonitis: This is a type of interstitial lung disease caused by an allergic reaction to inhaled particles, such as dust or mold spores. Mosaic attenuation is commonly seen in hypersensitivity pneumonitis.

Mosaic attenuation is a nonspecific finding and can be caused by a variety of underlying conditions. Further imaging studies, laboratory tests, and clinical examination are usually necessary to determine the specific cause of mosaic attenuation in the lung.