10
Diagnosis
Table 4. Histopathology Patterns and Features
UIP Probable UIP
Indeterminate
for UIP
Alternative
Diagnosis
• Dense
fibrosis with
architectural
distortion (i.e.,
destructive
scarring and/or
honeycombing )
• Predominant
subpleural and/
or paraseptal
distribution of
fibrosis
• Patchy
involvement of
lung parenchyma
by fibrosis
• Fibroblast foci
• Absence of
features to
suggest an
alternate
diagnosis
• Some histologic
features from
column 1 are
present but to
an extent that
precludes a
definite diagnosis
of UIP/IPF
And
• Absence of
features to
suggest an
alternative
diagnosis
Or
• Honeycombing
only
• Fibrosis with
or without
architectural
distortion, with
features favoring
either a pattern
other than
UIP or features
favoring UIP
secondary to
another cause
a
• Some histologic
features from
column 1,
but with
other features
suggesting an
alternative
diagnosis
b
• Features of
other histologic
patterns of IIPs
(e.g., absence of
fibroblast foci or
loose fibrosis) in
all biopsies
• Histologic
findings
indicative
of other
diseases (e.g.,
hypersensitivity
pneumonitis,
Langerhans cell
histiocytosis,
sarcoidosis,
LAM)
a
Granulomas, hyaline membranes (other than when associated with acute exacerbation of IPF, which
may be the presenting manifestation in some patients), prominent airway-centered changes, areas
of interstitial inflammation lacking associated fibrosis, marked chronic fibrous pleuritis, organizing
pneumonia. Such features may not be overt or easily seen to the untrained eye and oen need to be
specifically sought.
b
Features that should raise concerns about the likelihood of an alternative diagnosis include a
cellular inflammatory infiltrate away from areas of honeycombing, prominent lymphoid hyperplasia
including secondary germinal centers, and a distinctly bronchiolocentric distribution that could
include extensive peribronchiolar metaplasia.
