16
Diagnosis
Figure 2. Three-density Pattern
Table 6. Histopathological Criteria for the Diagnosis of HP
(Other than "Hot-Tub Lung"
a
)
Matter Typical Sources HP "Disease"
Nonfibrotic HP (cellular HP)
Typical histopathological
features of nonfibrotic
HP—at least one biopsy
site showing all three of the
following features:
1. Cellular interstitial
pneumonia
• Bronchiolocentric
(airway-centered)
• Cellular NSIP-like
pattern
• Lymphocyte-
predominant
Both of the following features
(1 and 2 from first column) in
at least one biopsy site:
1. Cellular interstitial
pneumonia
• Bronchiolocentric
(airway-centered)
• Cellular NSIP-like
pattern
• Lymphocyte-predominant
At least one biopsy site
showing one of the
following :
• 1 or 2 from the first
column
• Selected IIP patterns
◦ Cellular NSIP
pattern
◦ Organizing
pneumonia pattern
◦ Peribronchiolar
metaplasia without
other features to
suggest fibrotic
HP and
High-resolution computed tomography (A) inspiratory and (B) expiratory images from
a patient with hypersensitivity pneumonitis demonstrating the three different densities:
high attenuation (ground-glass opacity) (red stars), lucent lung (regions of decreased
attenuation and decreased vascular sections) (red arrows), and normal lung (black
arrows), which are sharply demarcated from each other.
