肺部HRCT与病理解剖

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首先介绍一下正常hrct和病理解剖

a：肺动脉分枝呈锐角
b：肺静脉分枝呈直角

星号：支气管血管束（bronchovascular bundle ）
箭头：正常肺小叶结构或次级肺小叶（pulmonary lobule或secondary pulmonary lobule ）和小叶间隔（interlobular septa ），其大小约 1 至2.5 cm 。
normal interlobular septa are seen occasionally as subpleural,

fine, linear structures forming polygons, 1 to 2.5 cm in diameter.

these septa define the pulmonary lobule, which is also referred

to as the secondary pulmonary lobule (arrows delimit one).

two bronchiolovascular bundles are seen within the lobule.

the black line marks the interlobular septum with veins (v).
黑线标记的是小叶间隔和静脉
the oval marks one bronchiolovascular bundle within the lobule.
卵圆形标记的是小叶内的支气管血管束
in a second bronchiolovascular bundle to the left, the artery (a)

and bronchiole (b) are marked.

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1.bronchovascular interstitium (surrounds the bronchovascular bundle)
   支气管血管束周围间质间隙（中轴间质间隙）
2.centrilobular interstitium (surrounds the distal bronchiolovascular bundle)
   中心小叶间质间隙（实质间质间隙指肺泡内的间质组织间隙）
3.interlobular septal interstitium (often seen as lines perpendicular to the pleura)
    小叶间质间隙
4.pleural interstitium 胸膜下间质间隙

正常肺间质hrct一般不能见到。下面以肺癌性淋巴转移病例以上改变：



note the numerous polygonal lobules outlined by thickened interlobular septa.

in some cases, the thickened terminal bronchiolovascular bundle,

representing tumor in the centrilobular interstitium,

is seen at the center of the lobule (see black polygon).

a large airway at the upper right (b) shows thickening of its wall

by tumor in the bronchovascular interstitium, and the black,

hilar lymph nodes (l) are partially replaced by tumor.


增厚的小叶间隔呈多边形改变，可见支气管血管束末梢增粗。血管支气管周围间质增厚。



a pulmonary lobule outlined by tumor-filled interlobular septa is at the upper left.

bronchiolovascular bundle and interstitium are marked with an asterisk.
（如黑线描绘所示为肿瘤侵润增厚的小叶间隔，星号所示为增厚的血管支气管束和周围间质）


this vein (v) is surrounded by tumor in lymphatics.

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basic hrct patterns  hrct基本表现
lines, nodules, consolidation, ground-glass opacity, and cysts（线状影、结节、实变、磨玻璃影、囊肿）



basic hrct patterns: linear abnormalities

linear abnormalities include:
a) thickened interlobular septa (image 1)小叶间隔增厚
b) bronchovascular interstitial thickening (image 1)血管支气管间质增厚
c) reticular change (image 2). 网状改变
图一

图二

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basic hrct patterns: nodules
definition:
a nodule is a rounded density that does not correspond to a vessel.

it represents either a spherical structure or a linear structure cut in cross section.

location of nodules:
the anatomic distribution of nodules--centrilobular, random, or interstitial--helps to identify

potential causes； for example, bronchopneumonia gives nodules in a centrilobular distribution.

in image 1, multiple nodular densities of varying size are seen in the right lung.

note that they are clustered in a line following the course of a bronchus in this example of

bronchopneumonia. the larger nodular densities represent foci of lobular consolidation
(1 to 2.5 cm in size).

the tiny nodules (1 to 2 mm in size) represent distal bronchiolar inflammation.

the location of the nodules is centrilobular (see next page).

causes of nodules include tumor,pneumoconioses,   endobronchial disease,

mucous plugs,infectious and non-infectious granulomas, and hypersensitivity pneumonia.

导致结节的病因有：肿瘤、感染和非感染性肉芽肿 、尘肺、粘液栓、支气管病变、过敏性肺炎等。
图一

\\\"tree-in-bud\\\" pattern

some of the tiny centrilobular nodules are connected by thin, branching, linear structures.

this appearance, which is referred to as \\\"tree-in-bud,\\\" represents inflammation in branching

bronchioles.
图二


]

gross appearance of bronchopneumonia

this lung shows a more diffuse bronchopneumonia than is seen in the hrct above.

large arteries and airways may be seen cut in cross section or longitudinally.

distributed fairly uniformly in the intervening parenchyma are small,

pale nodules and lines, some of which are branching.

these represent centrilobular airways filled with pus,

which extends into the alveoli to a variable degree, accounting for the mild size differences.

]

histologic section of bronchopneumonia

a section of one of the centrilobular nodules shown above has an airway (center) filled with

exudate, which is also present in the surrounding alveoli.

by definition, bronchopneumonia is confined to the centrilobular region,

and the presence of air in the adjacent lung gives the nodular appearance on hrct.

when the exudate fills the whole lobule, the resulting hrct pattern is that of larger nodules as

seen above.

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note the unmarked nodules along the fissural pleura bilaterally.

architectural distortion is seen here as angulation along the major fissure on the right.
大体标本胸膜结节：

the pleural surface of this lung shows multiple nodules corresponding to the pleural nodules

noted in the first image above.


病变侵犯血管支气管、小叶间隔、胸膜。部分支气管血管结节已侵润到外带的小叶中心区域。
与hrct表现一致。
the distribution of lesions is bronchovascular, interlobular septal, and pleural.

some of the bronchovascular nodules extend peripherally into the centrilobular regions.

the distribution is the same as that seen in the hrct images.


non-necrotizing granuloma composed of epithelioid histiocytes, multinucleated giant cells,

and lymphocytes。

differential diagnosis of nodules and lines on hrct:

diagnoses include sarcoidosis and lymphangitic tumor.

architectural distortion, as shown on image 2 is frequent in sarcoidosis,

but not with lymphangitic tumor.

summary of diagnostic features of sarcoidosis on hrct

1、pleural, bronchovascular and interlobular septal interstitial nodules

2、upper lung predominance common

3、architectural distortion frequent

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小叶中心结节很少出现在胸膜表面。胸膜下结节往往距胸膜或斜裂5－10mm。结节增大时可达胸膜。
centrilobular nodules spare the pleural surfaces. the most peripheral nodules are usually

centered 5-10 mm from fissures or the pleural surface, although large nodules can touch

the pleura.
小叶中心结节centrilobular nodules

胸膜下结节peripheral nodules




this diagram illustrates lymphangitic tumor highlighting anatomic structures--

interlobular septa and centrilobular nodules.



here, the regularly-spaced centrilobular nodules remain when the linear structures are
   taken away.



tree-in-bud
pattern represents several centrilobular nodules connected by thin, branching,

linear structures. these often represent connected nodules of a rosette.
树芽征tree-in-bud

differential diagnosis of centrilobular nodules on hrct:
小叶中心结节的鉴别诊断：
小叶中心结节常见于急性或慢性支气管感染，如细菌、病毒或真菌，往往合并支气管扩张症或网状纤维化。也可出现在炎性病变如过敏性肺炎、呼吸性细支气管炎、闭塞性细支气管炎并机化性肺炎、尘肺、结节病、哮踹、自身免予缺陷疾病、闭塞性细支气管炎等。
centrilobular nodules usually result from acute or chronic bronchiolar infections--bacterial,

viral, or fungal--especially those associated with bronchiectasis or cystic fibrosis.

they also occur in inflammatory conditions such as hypersensitivity pneumonia,

respiratory bronchiolitis, bronchiolitis obliterans organizing pneumonia, pneumoconioses,

sarcoidosis, asthma, autoimmune and immunodeficiency diseases, and bronchiolitis obliterans.

summary of diagnostic features of diffuse bronchitis/bronchiolitis
on hrct
弥漫性（细）支气管炎的hrct表现：
1、diffuse well- and poorly-defined centrilobular nodules
     弥漫分布边缘清楚或不清的小叶中心结节
2、tree-in-bud pattern
     树芽征
3、thickening of bronchial walls
     支气管壁增厚
4、± patchy pneumonic consolidation
     有/无肺炎实变灶

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nodules said to have a random distribution are randomly distributed relative to

structures of the lung and secondary lobule. in general, they appear evenly distributed

throughout the lung, and tend to involve both lungs symmetrically. nodules can usually

be seen to involve the pleural surfaces and fissures, but lack the subpleural predominance

often seen in patients with a perilymphatic distribution.

small random nodules are often seen in patients with hematogenous metastases,

miliary tuberculosis, and miliary fungal infections. when very extensive,

sarcoidosis may mimick this pattern.

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*identification of fissure: vessels from upper and lower lobes branch
and taper toward the fissure and are absent at the fissure.
通过上图可见小叶中心结节、血管末梢结节、胸膜结节、斜裂结节（f标记）


random nodules

the term random is used to describe nodules distributed haphazardly throughout the lungs

--along the pleura and fissures, at the ends of small arteries,

and also in a centrilobular location (diagram), as opposed to centrilobular nodules,

which have a single anatomic location. random nodules are typically uniformly distributed

bilaterally, and no one anatomic location predominates.

hint: think of a pizza with olives scattered haphazardly (random) vs pepperoni placed
uniformly (centrilobular).

differential diagnosis of random nodules on hrct:

diagnoses include hematogenous metastasis (particularly from thyroid, kidney, and breast)

and miliary infections. langerhans&#39； cell histiocytosis, sarcoidosis,

and silicosis are common causes of nodules, but such nodules are rarely diffuse
and haphazard.

histologic differential diagnosis: hematogenous metastatic tumor,

which is usually, but not always, from an extrapulmonary source.


summary of diagnostic features of numerous hematogenous
metastatic nodules on hrct

1、usually random distribution
2、often smooth, well-defined
3、varying size common

comment:

random nodules occur along the pleura and fissures, in a centrilobular location,

and in the bronchovascular region. the bronchovascular nodules in the case of

random nodules are seen at the ends of small arteries

and not in the proximal bronchovascular interstitium.

nodules in lymphangitic tumor and sarcoidosis are frequently seen

in the central bronchovascular interstitium.

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淋巴管周围性 (perilymphatic) :指异常 (如结节 )分布于相当肺淋巴管所在的部位。明显和肺门旁
支气管血管周围间质、小叶中央间质、小叶间隔和胸膜下区有关的结节是典型的淋巴管周围分布。



on hrct, nodules are seen in relation to:

1) pleural surfaces；



2) interlobular septa；



3) the peribronchovascular interstitium in the parahilar regions；



and/or 4) peribronchovascular interstitium in a centrilobular location.

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peribronchovascular interstitium支气管血管周围间质

下面以一例“凯泼希肉瘸”病例介绍：
凯泼希肉瘸(kaposi&#39；s sarcoma,简称ks)又名特发性出血性肉瘤,皮肤多发性出血性肉瘤,卡波西(氏)肉瘤:一种多病灶恶性新生血管增殖症。肿瘤常见于头颈部和四肢皮肤，偶见于内脏。患者中有半数出现口腔病损，表现为无痛性、紫红色或紫褐色的、大小形状不一、扁平或隆起的病损。牙龈和硬软腭为好发部位。通常认为，在没有使用过免疫抑制剂的患者中出现卡波西肉瘤病损时，基本上可诊断是爱滋病。卡波西氏肉瘤是艾滋病患者最常见的肿瘤。


centrilobular location 小叶中心分布



interlobular septal thickening小叶间隔增厚



differential diagnosis of hrct by abnormality:

a) smooth thickening of the interstitium is seen with lymphangitic tumor, lymphoma,

edema, and kaposi&#39；s sarcoma, but is uncommon in sarcoidosis.

b) diffuse nodules affecting the pleura, interlobular septa, and bronchovascular

and centrilobular regions can be seen with sarcoidosis, lymphangitic tumor, lymphoma,

kaposi&#39；s sarcoma, hematogenous infection, and metastases 。hematogenous infection

usually gives nodules of uniform size.

c) smooth interstitial thickening together with diffuse interstitial nodules occur with

lymphangitic tumor. less likely diagnoses are lymphoma, kaposi&#39；s sarcoma, sarcoidosis,

and the combination of edema with hematogenous metastases or infection.

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