【影像征象】樹芽征 | The tree-in-bud sign

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The appearance of the tree-in-bud sign is closely linked to the anatomy of the secondary pulmonary lobule.
樹芽征表現與次級肺小葉密切相關。

The diseased small airway often becomes visible as fluid replaces gas in the small airway and inflammation thickens the bronchiolar walls.This results in a V- or Y-shaped branching pattern, which together with centrilobular nodularity forms the tree-in-bud sign.

小氣道病變由于液體代替小氣道內氣體和支氣管管壁炎性增厚而可識別。V形或Y形的分枝狀影和小葉中心結節一起形成樹芽征。

Although the tree-in-bud signhas primarily been used as a descriptive term for endobronchial spread of Mycobacterium tuberculosis, it is now recognized as a common pattern that can be seen in many pulmonary diseases and disorders including infection (most common), aspiration, and rarely neoplastic conditions (such as low-grade adenocarcinoma).
盡管樹芽征最初用于描述結核分枝桿菌的支氣管內播散，現為多種肺疾病的一種常見征象，包括感染（最常見）、吸入、少見腫瘤性病變（低級別腺癌）。

In Mycobacterium tuberculosis, the tree-in-bud sign results from impaction of caseous material in the bronchioles of the secondary pulmonary lobule.
在結核分枝桿菌中，樹芽征是由于干酪質物質在次級肺小葉細支氣管中的嵌塞所致。

Identification of the tree-in-bud sign along with other imaging findings such as bronchial wall thickening or narrowing, bronchiectasis, consolidation, cavitation, and/or necrotic lymphadenopathy, as well as an appropriate exposure history, supports the diagnosis.

樹芽征合并其它影像學表現，如支氣管壁增厚或變窄、支氣管擴張、實變、空洞和/或淋巴結壞死及合適的暴露史可支持診斷。

This is in contradistinction to non-tuberculous mycobacterial pneumonia in which centrilobular or tree-in-bud nodularity and bronchiectasis with volume loss (usually most severe in the right middle lobe and lingula) predominate.
這與非結核分枝桿菌性肺炎形成對比，其中以小葉中心或樹芽狀結節和支氣管擴張為主，伴肺容積減?。ㄍǔＴ谟抑腥~和舌葉最嚴重）。

Non-tuberculous mycobacterial pneumonia usually occurs in middle-aged to elderly women who often have low body mass index and kyphoscoliosis.
非結核分枝桿菌肺炎通常發生在中年至老年婦女，她們往往體重指數低和脊柱后凸。

The tree-in-bud sign may also be present in other types of pneumonia (such as Staphylococcus aureus and Haemophilus influenzae) as pus or inflammatory secretions impact the distal small airways.
樹芽征也可見于其他類型肺炎（如金黃色葡萄球菌和流感嗜血桿菌），由于膿液或炎性分泌物影響遠端小氣道。

In patients with aspiration, a gravitational and lower lung predominance of the tree-in-bud pattern is often observed.
在吸入性患者中，樹芽征常以重力區和下肺為主。

A rare but underrecognized cause of the tree-in-bud sign is distant metastatic disease (e.g. from breast, hepatic, ovarian, prostatic, and renal primaries). The appearance is due to carcinomatous endarteritis—inflammatory intimal hyperplasia of the small pulmonary arteries secondary to filling with tumor cells.
罕見但未被充分認識病因是遠處轉移性疾病（例如來自乳腺、肝臟、卵巢、前列腺和腎臟原發灶）。表現是由于內膜炎-小肺動脈繼發于腫瘤細胞填充的炎性內膜增生。