What is the role of HRCT in the workup of eosinophilic granuloma (histiocytosis X)?

Updated: Mar 29, 2018
  • Author: Eleanor M Summerhill, MD, FACP, FCCP; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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HRCT of the chest may be virtually diagnostic in the appropriate clinical setting. Pathognomonic findings include nodules and cysts, predominantly in the mid and upper lung zones, with sparing of the costophrenic regions. The nodules may be cavitary and variable in size. Likewise, the cysts may be of various diameters and wall thicknesses. A broad differential diagnosis must be considered in the following situations:

  • If only nodules are present on HRCT, the findings are nonspecific, and a number of other granulomatous disorders cannot be excluded radiographically.

  • When cysts are an isolated finding, LAM must be considered as well. Unlike PLCH, LAM is usually uniformly distributed throughout the lungs. Sparing of the costophrenic angles supports a diagnosis of PLCH.

  • Emphysema is usually distinguishable, as walls do not surround the cystic spaces found in emphysema. However, extensive emphysema is sometimes difficult to differentiate from PLCH.

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