Usual Interstitial pneumonia and Nonspecific Interstitial Pneumonia Nitra and the Gangs.
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Usual Interstitial Pneumonia (UIP) Most common & basic pathologic pattern Can found as Idiopathic. Connective tissue-related. Hypersensitivity. Drugs. Smoking. Asbestosis. Non-specific Interstitial Pneumonia (NSIP) Common & non-specific. Can found as Idiopathic. Connective tissue-related. Hypersensitivity. Drugs. Infection Immunosuppression including HIV.
UIP & NSIP > 50% of interstitial lung disease. Share many similar characters: Bibasilar subpleural distribution. Finally fibrotic. Can be found in the same patient. Could be in continuum of epithelial injury and dysregulated repair. Prognosis: Much better in NSIP. Better prognosis of UIP in CNT than of UIP in IPF.
UIP Usual Interstitial Pneumonia
UIP: 3 Pathological hallmarks A heterogeneous appearance at low magnification, with alternating areas of normal lung, interstitial inflammation, fibrosis, and honeycombing. spatial heterogeneity temporal heterogeneity patch-work pattern.
S10 A MB
S10 A MB UIP NSIP
v v TB A
Temporal/Spatial Heterogeneity on CT Johkoh et al, proposed 1. Asymmetry distribution. 2. Lobular heterogeneity; various findings including normal to end stage fibrosis in one 2 o pulmonary lobule Johkoh et al, European J Radiology 2014
UIP: 3 Pathological hallmarks Predominantly distributed in perilobular areas: perilobular (periacinar) pattern. HRCT: Intralobular reticular opacities. Irregular pleural surface. Irregular thickening of interlobular septa. Irregular thickening of bronchovascular bundles.
V A MB V ILS UIP in early phase:perilobular fibrosis FF
S10 A MB MB MB TB Interlobular septum Intralobular venule
UIP Fibrosis along the pleura, interlobular septa, and intralobular vein V V RB V V A MB intralobular vein
RB A ILS v Marked fibrosis at the pleuro-septal junction (wedge-shaped) Hyperplasia of smooth muscle in the fibrosis v
Upper lobe image of the same case Fine nodular lesion arising from the pleura Fine nodular lesion arising from the pleura
63 65 Courtesy of Drs. Ogura and Itoh H.O
UIP: 3 Pathological hallmarks Honeycombing: The end-stage hallmark. Consisting of collapsing of multiple fibrotic alveoli and dilation of alveolar duct and lumen. Size: few mm - few cm. Aragawa & Honma, AJR 2011
Histology of Honeycombing MB ( alveolar tip) Histologically, collapsed alveoli, dilated alveolar ducts in the cyst wall with smooth muscle hyperplasia. Bronchiolar epithelium lining the cystic spaces (bronchiolization)
V V V ILS V PV Pleural indentation at the interlobular septa where alveoli are collapsed. A MB br A PA
Autopsy lung of IPF/UIP 3~5 mm-size concave-convex pleural surface
Honeycombing HRCT: Glossary term in Fleischner Society Clustered cystic air spaces, typically 3 10 mm but occasionally as large as 2.5 cm. Usually subpleural & well-defined walls. Presence of typical honeycombing in HRCT: high specificity but low sensitivity. Indicate poor prognosis not only in patients with UIP but also in NSIP. Johkoh et al, European J Radiology 2014
Honeycombing in CT 1. Tangential view of traction bronchiolectasis. 2. Dilatation of peripheral airspace due to surrounded fibrosis. In UIP: type 2 > type 1 cysts. Johkoh et al, European J Radiology 2014
Traction Bronchiectasis Bronchiectasis resulting from fibrosis Corkscrew appearance Absent mucous plugging A/W other findings of fibrosis e.g. honeycombing UIP = common cause
Histopathological criteria for UIP pattern (2011) UIP pattern (All four criteria) Probable UIP pattern Possible UIP pattern (All three criteria) Not UIP pattern (Any of the 6 criteria) Evidence of marked fibrosis/architectural distortion, ± honeycombing in a predominantly subpleural /paraseptal distribution Presence of patchy involvement of lung parenchyma by fibrosis Presence of fibroblastic foci Absence of features against diagnosis of UIP suggesting an alternate diagnosis (see fourth column) Evidence of marked fibrosis/architectural distortion, ±honeycombing Absence of either patchy involvement or fibroblastic foci, but not both Absence of features against a diagnosis of UIP suggesting an alternate diagnosis (see fourth column) or Honeycomb changes only Patchy or diffuse involvement of lung parenchyma by fibrosis, with or without interstitial inflammation Absence of other criteria for UIP (see UIP pattern column) Absence of features against a diagnosis of UIP suggesting an alternate diagnosis (see fourth column) Hyaline membranes Organizing pneumonia Granuloma Marked interstitial inflammatory cell infiltrate away from honeycombing Predominant airway centered changes Other features suggestive of an alternate diagnosis (Raghu G et al. AJRCCM, 183: 788-824, 2011)
HRCT Criteria for UIP Pattern An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence based guidelines for diagnosis and management. Am J Respir Crit Care Med 2011.
HRCT Histology Vertical distribution Axial distribution Intralobular Honeycombing Temporal heterogeneity (Patchy involvement or fibroblast + fibrosis)
UIP 50% of patients, Typical HRCT findings- a confident diagnosis w/o surgical biopsy. HRCT may mimic other interstitial lung diseases, particularly NSIP.
Combination of HRCT and surgical lung biopsy for the Diagnosis of IPF HRCT UIP Surgical lung biopsy pattern (when performed) UIP Probable UIP Possible UIP Nonclassifiable fibrosis Not UIP Diagnosis IPF Yes No
Combination of HRCT and surgical lung biopsy for the Diagnosis of IPF HRCT Possible UIP Inconsistent with UIP Surgical lung biopsy pattern (when performed) UIP Probable UIP Possible UIP Nonclassifiable fibrosis Not UIP UIP Probable UIP Possible UIP Non-classifiable fibrosis Not UIP Diagnosis IPF Yes Probable No Possible No
IPF A specific form of chronic, progressive fibrosing interstitial pneumonia of unknown cause. Occurring primarily in older adults. Limited to the lungs, and associated with the histopathologic and/or radiologic pattern of UIP.
IPF The diagnosis of IPF requires: Exclusion of other known causes of interstitial lung disease. The presence of a UIP pattern on HRCT in patients not subjected to surgical lung biopsy. Specific combinations of HRCT and surgical lung biopsy pattern in patients subjected to surgical lung biopsy.
Natural History of IPF Variable and unpredictable. Majority: gradual worsening of lung function over years. Minority: stable or declines rapidly. Some: Episodes of acute respiratory worsening despite previous stability. Acute exacerbation An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence based guidelines for diagnosis and management. Am J Respir Crit Care Med 2011.
Diagnostic algorithm for IPF
NSIP Nonspecific Interstitial Pneumonia
NSIP Characterized by spatially homogenous alveolar wall thickening with underlying inflammation and/or fibrosis. ATS/ERS classification of IIPs: 2002: considered NSIP as provisional diagnosis. 2013: accepted idiopathic NSIP as a specific clinicopathologic entity. More commonly in women and younger patients but otherwise demonstrates similar clinical features to UIP
NSIP
Normal and NSIP Normal NSIP
Electron microscopy Ⅱ 型 Normal NSIP
NSIP 2 histologic subtypes: based on the relative amounts of lung inflammation & fibrosis. Cellular type. o Greater proportion of inflammatory histologic findings. o More favorable prognosis relative to fibrotic NSIP. o Quite uncommon. Fibrotic type.
Cellular-NSIP Fibrotic-NSIP
TB, terminal bronchiole F-NSIP PA MB TB
ILS ILS, interlobular septum ILS
HRCT features of UIP VS NSIP Distribution UIP NSIP Axial Subpleural Peribronchovascular Subpleural Immediate subpleural sparing Craniocaudal Basal Basal Diffuse Within lobule Perilobular/ Periacinar Nonspecific
HRCT features of UIP VS NSIP Pattern UIP NSIP Abnormality findings Common: Honeycombing Reticulation Uncommon: GGO (less extensive) Common: GGO Reticulation Traction bronchiectasis Uncommon: Honeycombing (less extensive)
GGO and intralobular lines Traction bronchiectasis No honeycombing Peribronchovascular distribution Immediate subpleural sparing
NSIP Highly heterogeneous of clinical progression Silva et al follow-up 23 pts with biopsyproven NSIP (34-155 months) 28% of 18 patients o Initial findings suggestive of NSIP but follow-up CT suggestive of IPF pattern. o Mixed or fibrotic NSIP at biopsy. None of 4 NSIP with a cellular pattern at biopsy progressed to an IPF pattern at CT. No CT features to predict changes over time. Silva et al, Radiology 2008
NSIP? NSIP may represent an early stage of UIP? NSIP pattern seen at biopsy may simply be indicative of relatively inactive UIP. Katzenstein et al; none of 20 patients with IPF showing NSIP in preceding biopsy. Silva et al, Radiology 2008
NSIP Intralobular line with loss of normal architecture and destroyed lung
NSIP Intralobular line with loss of normal architecture and destroyed lung
NSIP 5 year later
NSIP
NSIP Before 5-year later
NSIP Before 5-year later
2006
2009
UIP and f-nsip Can be identical on HRCT. Irreversible & not improved with steroid. UIP & f-nsip in CNT: little different in prognosis.
Conclusion Typical HRCT findings of UIP, no need to biopsy. UIP and f-nsip: may difficult to differentiate. To diagnose IPF: Known causes of interstitial lung disease must be excluded. Acute exacerbation of IPF: an accepted phenomenon. Acute lung injury superimposed on a patchy fibrotic UIP-like background. Multidisciplinary discussion (MDD) - integral to the diagnosis and management of IPF.
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