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Type:
Educational Exhibit
Keywords:
Education and training, Education, CT-High Resolution, Thorax, Lung
Authors:
A. Modica, M. C. Calcagno, G. Iudica, M. Conte, M. J. Anzalone, I. Vizzini, L. A. Mauro, C. Vancheri, S. Palmucci; Catania/IT
DOI:
10.1594/ecr2017/C-2119
Findings and procedure details
UIP
UIP (Usual Interstitial Pneumonia),
typical pattern of IPF (Idiopathic Pulmonary Fibrosis),
is the commonest pulmonary interstitial disease,
with the worst prognosis compared to other pulmonary diseases.
- Epidemiology: UIP affects adults older than 50 years[1],
especially men[2],
with an incidence of 2.5 - 3/100.000 inhabitants[3]; risk factors include cigarette smoke,
environment pollution,
working exposition to inhalants agents such as asbestos,
metals and winged animals.
There is also a possible involvement of groups of genes[4].
There are two forms: idiopathic and secondary.
- Clinical features: UIP is characterized by non-specific and progressive symptoms such as dyspnea,
dry cough (usually associated with postero-inferior inspiratory crackles),
asthenia and fever,
with restrictive pulmonary deficit and reduction of DLCO.
- Radiological findings: honeycombing[5],
coarse reticulations,
traction bronchiectasis; these findings are characterized by spatial and temporal heterogeneity and a typical apico-basal gradient starting from lower lobes to upper lobes and from peripheryto central parenchyma with mainly sub-pleural and basal localizations (Fig. 1).
Ground-glass opacities are rarely recognizable.
There are three different radiological patterns: "usual" (Fig. 2),
"possible" (Fig. 3 - Fig. 4) and "inconsistent" (Fig. 5) each one having a different prognosis[6].
NSIP
The second most common pattern among interstitial lung diseases is NSIP.
There are two main subtypes: a "fibrotic" type (more common and with a worse prognosis) and a "cellular" (less common and with a better prognosis)[7].
- Epidemiology: NSIP usually affects adults over 40-50 years of age,
more often in caucasian population.
It can be secondary to collagen disorders,
drugs toxicity,
professional or environmental exposure to organic dust; it can also have an idiopathic etiology.
Collagenopathies related diseases are mostly common in in women,
while idiopathic disease shows no difference between sexes.
- Clinical features: Symptoms are non-specific and include dyspnea,
dry cough with restrictive lung disease at spirometry; in a third of the cases fever may also be present.
- Radiological findings: typical HRCT findings include ground-glass opacities predominance (Fig. 6 - Fig. 7 - Fig. 8) over fine reticulations [8]; in chronic patients HRCT shows traction bronchiectasis often with parallel run toward sub-pleural areas or even with irregular appearance; the lesions show usually a symmetrical and bilateral distribution,
with relative sparing of sub-pleural areas (Fig. 9); in about 50% of the cases there is an apico-basal lesion distribution gradient with a prevalence to apical regions of the lesions.
Temporal homogeneity is another characteristic finding [9].
Honeycombing is rare.
HP
HP (Hypersensitivity Pneumonitis) is lung disease secondary to exposition to a sensitizing agent.
- Epidemiology: HP is strictly related to environmental or professional exposition to organic dust (Actinomyces Thermophilus contained in hay,
fungi,
animal proteins) or chemical agents.
Typical exposed subjects include agricultural workers,
wood workers,
pigeon breeders or industrial workers.
- Clinical features: HP can be divided into three manifestations: acute,
sub-acute and chronic [10].
The last one is characterized by diffuse fibrosis [11] and severe prognosis [12].
Acute onset begins after about 4 to 6 hours later the exposition to sensitizing agents,
with fever,
shivers,
general illness,
articular pains,
dry cough and dyspnea; these symptoms usually spontaneously resolve within two or three days avoiding exposure to the sensitizing agent; after many repeated attacks it can eventually evolve to pulmonary fibrosis.
Sub-acute type develops in a few days or weeks,
has an insidious onset with slowly progressive dyspnea,
dry cough,
fever and weight loss.
Chronic sub-type develops within months or years and is characterized by worsening dyspnea,
dry cough and leads to pulmonary failure.
- Radiological findings: (Fig. 10) HRCT shows ground-glass opacities predominantly distributed to middle-upper lung’s regions [12],
with a bilateral and symmetrical distribution (Fig. 11 – Fig.
12),
centrilobular micronodules with shaded edges (Fig. 10 – Fig. 11 – Fig. 12) [13],
“mosaic-like” oligemia areas (parenchymal inhomogeneity characterized by the presence of areas of increased and decreased parenchymal density),
air-trapping areas (Fig. 10 – Fig. 13 – Fig. 14) [14]; the simultaneous presence of air-trapping,
ground-glass opacities and sparing areas is known as the “head cheese pattern” (Fig. 10 – Fig. 15).
Honeycombing is a rare sign of reached chronic condition and its usual localization shows typical sparing of basal parenchyma.
Discussion
A correct differential diagnosis between UIP,
NSIP and HP is important because prognosis and treatment are different.
Regarding epidemiology,
UIP,
which is linked to cigarette smoke,
occurs primarily in men over 60 years of age; NSIP,
frequently connected to connective diseases,
is more common in women over 40-50 years of age [15]; HP is related to environment and working exposition to sensitizing agents.
Regarding radiological features,
in UIP the most important sign is macro-cystic honeycombing [16],
(Fig. 16 - Fig. 17),
coarse reticulation,
spatial and temporal heterogeneity,
and a typical apico-basal gradient – starting from lower lobes to upper lobes and from periphery to central parenchyma with mainly sub-pleural and basal localizations of lesions that usually show bilateral and symmetrical distribution; the most important features in NSIP are instead ground-glass opacity,
sub-pleural sparing and temporal homogeneity (Fig. 18 - Fig. 19); HP typical feature is the presence of nodules superimposed of ground-glass,
honeycombing can appear in chronic HP.
Honeycombing is macro-cystic in UIP with a localization at lower lobes and in sub-pleural areas; when present,
it is micro-cystic in NSIP; in HP it has a patchy localization [20].
Ground glass opacities are typical of NSIP,
but they can also be present in HP and are rare in UIP (in this case they can be expression of flare).
Prognosis is worse in UIP,
better in NSIP because of treatment; in HP symptoms regress after stopping exposition to antigen.