Head Cheese Sign

The head cheese sign refers to the combination of ground-glass opacity with mosaic attenuation and resembles the disgusting end result of combining various parts of an animal's head and face into a cold-cut.

The ground-glass opacity is caused by an infiltrative process, while the mosaic attenuation is caused by small airways obstruction (usually associated with bronchiolitis).

It is distinguished from mosaic perfusion alone by the presence of areas of increased attenuation and is distinguished from patchy ground-glass opacity or consolidation by the presence of air trapping (seen best on expiratory images).

It can be seen with:

• Hypersensitivity pneumonitis
• Desquamative interstitial pneumonia
• Respiratory bronchiolitis–interstitial lung disease
• Sarcoidosis
• Atypical infections with bronchiolitis (e.g., M. pneumoniae)

References

Webb WR. Thin-section CT of the secondary pulmonary lobule: anatomy and the image--the 2004 Fleischner lecture. Radiology. 2006 May;239(2):322-38.