Tree-in-bud Nodules in Asian Population

Full Article

AYH Wan, JSF Shum, WH Kwan, CS Cheng

Hong Kong J Radiol 2011;14:161-6

Objective: The tree-in-bud sign is a common finding on thin-section computed tomography of the lungs. However, the differential diagnosis of this common radiological finding is long and exhausting. Knowledge of its common causes together with the patient’s clinical history are essential to formulating an appropriate list of possibilities. This study aimed to evaluate the common causes of tree-in-bud opacities detected on computed tomographic thorax in Asians.

Methods: Records of 189 consecutive patients from two regional hospitals in Hong Kong underwent computed tomographic thorax and found to have tree-in-bud opacities during the period of January 2007 to June 2008 were retrospectively reviewed. This included a follow-up of their clinical progress, microbiological and histological findings.

Results: Mycobacterial infection was the commonest cause of such opacities, accounting for 68 (36%) of the cases. Other bacterial infection accounted for 54 (29%) cases. Whilst 31 (16%) were in patients with bronchiectasis and bronchiolectasis not associated with any bacterial infection, 12 (6%) of them had carcinoma of the lung, and 9 (5%) had other conditions.

Conclusion: This study suggests a list of differential diagnosis for commonly encountered tree-in-bud nodules on computed tomographic scans among Asians; the commonest being infection, particularly tuberculosis (which is much more prevalent than in the western populations). Non-bacterial bronchiectasis and bronchiolectasis are the next most common cause. Neoplasia, especially carcinoma of the lung, accounts for a small proportion. In contrast to western studies, cystic fibrosis, allergic bronchopulmonary aspergillosis, hypersensitivity pneumonitis, and pneumocystic carinii were not encountered in our sample.





目的:肺部薄層CT經常見樹芽狀徵象,可是這種情況的鑑別診斷很難。要了解患者的病史,加上對 於這種樹芽徵病因的認識,才可以歸納出病人發病可能的原因。本研究評估亞洲人中胸部CT呈樹芽 狀陰影的普遍病因。

方法:回顧研究2007年1月至2008年6月期間於香港兩所分區醫院內連續189名作胸部CT掃描並發現 有樹芽狀陰影的病人紀錄,包括臨床表現、微生物學及組織學的發現。 結果:結核菌感染為導致胸部CT呈樹芽狀陰影的最普遍原因,佔病例的36%(68例);其他細菌 感染佔29%(54例)。31例(16%)為沒有細菌感染的支氣管擴張症以及細支氣管擴張症;12例 (6%)為肺癌,另9例(5%)屬其他疾病。

結論:本研究歸納出亞洲人胸部CT呈樹芽狀陰影的普遍鑑別診斷,其中最常見的是感染,尤其是肺 結核(結核比在西方國家更普遍)。其次是沒有細菌感染的支氣管擴張症以及細支氣管擴張症。腫 瘤(尤其是肺癌)佔病例的較少數。外國文獻中有關於囊腫性纖維化、過敏性支氣管肺曲霉病、過 敏性肺炎及肺囊蟲的記載,可是並未在本研究的病例中發現。