12
Diagnosis
Table 4. Chest HRCT Scan Features of the Nonfibrotic HP
Pattern
HRCT
Pattern Typical HP Compatible with GHP
Indeterminate
for HP
Description e "typical HP"
pattern is suggestive of
a diagnosis of HP.
It requires:
a. at least one HRCT
abnormality
indicative of
parenchymal
infiltration and
b. at least one HRCT
abnormality
indicative of small
airway disease,
both in a diffuse
distribution.
"Compatible-with-HP"
patterns are nonspecific
patterns that have been
described in HP.
N/A
Relevant
radiological
findings
HRCT abnormalities
indicative of
parenchymal
infiltration:
• GGOs
• Mosaic
attenuation
a
Parenchymal abnormalities:
• Uniform and subtle
GGOs
• Airspace consolidation
• Lung cysts
N/A
HRCT abnormalities
indicative of small
airway disease:
• Ill-defined,
centrilobular
nodules
• Air trapping
Distribution of
parenchymal abnormalities:
• Craniocaudal: diffuse
(variant: lower lobe
predominance)
• Axial: diffuse (variant:
peribronchovascular)
Distribution of
parenchymal
abnormalities:
• Craniocaudal:
diffuse (with or
without some basal
sparing )
• Axial: diffuse
a
Mosaic attenuation corresponding to parenchymal infiltration is created by GGOs adjacent to
normal-appearing lung.
