Clinical diagnosis
Case 174
【Progress】
She was given antibiotics AB penicillin, predonin 20 mg (increasing from 10mg). Further, she received respiratory inhalation of short acting beta2 agonist. She got non-steroid anti-inflammatory drug (RILICA). These medicines made her soothing respiratory disorder.
【Discussion】
Histologic findings in human lung revealed there are units called a primary lobule and a secondary lobule. A primary pulmonary lobule is the distal area of a respiratory bronchioles and composes of 30 to 50 secondary pulmonary lobules. A primary pulmonary lobule is not so often recognized on chest CT. Meanwhile, a secondary pulmonary lobule is the distal area of a terminal bronchioles and composes of alveolar ducts and 5-15 alveoli (1-3). Its size is 10 to 20 mm (1-3). A secondary pulmonary lobule is the most basic anatomy to interpret the lesion in lung on CT. Then, a secondary pulmonary lobule is merely called a pulmonary lobule.
Pulmonary lobule is outlined by thin septum. Pulmonary artery, bronchioles and lymphatic vessel travel in the center of pulmonary lobule which is then called bronchus-vascular bundle, while pulmonary vein and lymphatic vessel travel in a septum of pulmonary lobule, namely in the margin of pulmonary lobule (3).
Centrilobular lesions include bronchopneumonia, mycoplasma, hypersensitivity pneumonia, tuberculosis, non-tuberculosis mycobacterial disease, respiratory bronchitis in smokers, mineral dust air way disease, diffuse pan-bronchiolitis, and follicular bronchiolitis (3, 4). Since they almost arise from air infection, follicular bronchiolitis might come from antigens from air. Margin-lobular lesions include pulmonary edema, lymphangitic carcinoma and sarcoidosis. Random distribution lesions include hematogenic metastasis and sarcoidosis(3, 4). Emphysema is also categorized according to the occurring site into three types: centrilobular, para-septal and pan-lobular.
Diffuse pan-bronchiolitis (DPO) is known to be associated with chronic sinusitis and its occurrent incidence is getting decreased because of the use of macrolide antibiotics (4). Meanwhile, follicular bronchiolitis (FB) is associated with rheumatoid arthritis or Sjogren disease. Histologic difference is that lymphocytes, histiocytes and neurocytes infiltrate around terminal bronchiole and bronchus-vascular bundle for DPO (4), while lymphocytes proliferation with germ cell formation such as hyperplasia of BALT (bronchus associated lymphoid tissue) for FB (5-8). The proliferative lymphoid tissue protrudes in the lumen of terminal bronchus, inducing bronchiolitis.
FB is one of the proliferative lymphoid tissue diseases: intrapulmonary lymph-node, FB and interstitial lymphoid pneumonia. Histologically, proliferative lymphoid tissue is localized at bronchus-vascular bundle for FB, while interstitial lymphoid pneumonia infiltrates apical septum as well as bronchus-vascular bundle (9).
As radiologic findings, “tree-in-bud” and/or “cotton-in-bud” are shown on chest CT (10). These signs appear as the centrilobular lesions at the margin of the whole lung. In our case, she suffered from rheumatoid arthritis and presented in our hospital for moisture cough and hard to breathe. Chest CT showed the appearance of “tree-in-bud” in the whole lung, indicative of FB
【Summary】
We present a seventy eight-year-old female for being hard to breathe and moisture cough. She was ailing rheumatoid arthritis. Chest CT showed the appearance of “tree-in-bud” in the whole lung. Based on both history of illness and typical CT findings, she was diagnosed as follicular bronchiolitis. It should be in borne that pulmonary lobule called on CT indicates secondary lobule which is the distal area (10 to 20 mm in size) of a terminal bronchus, composing of bronchus-vascular bundle in the center and septum in the margin. Follicular bronchiolitis is one of the centrilobular lesions which arise from air infection. Histologic examination of follicular bronchiolitis shows lymphocytes proliferation with germ cell formation such as hyperplasia of BALT (bronchus associated lymphoid tissue) which protrudes and occludes lumen of terminal bronchus. Histologic difference between follicular bronchiolitis and interstitial lymphoid pneumonia is that proliferative lymphoid tissue is localized at bronchus-vascular bundle for FB, while interstitial lymphoid pneumonia infiltrates apical septum as well as bronchus-vascular bundle. Centrilobular lesions appear as “tree-in-bud” and/or “cotton-in-bud” on chest CT.
【References】
1.Heitzman ER, et al. The secondary pulmonary lobule: a practical concept for interpretation of chest radiographs. I. Roentgen anatomy of the normal secondary pulmonary lobule. (1969) Radiology. 93 (3): 507-12.
2.Webb WR. Thin-section CT of the secondary pulmonary lobule: anatomy and the image--the 2004 Fleischner lecture. (2006) Radiology. 239 (2): 322-38.
3.Itoh H, et al. Diffuse lung disease: pathologic basis for the high-resolution computed tomography findings. Journal of thoracic imaging. 1993;8 : 176-88.
4.Poletti V, et al. Diffuse panbronchiolitis. European Respiratory Journal 2006 28: 862-871
5.Tashtoush B, et al. Follicular Bronchiolitis: A Literature Review. J Clin Diagn Res. 2015 Sep; 9(9): OE01–OE05.
6.Yuksekkaya R, et al. Pulmonary involvement in rheumatoid arthritis: multidetector computed tomography findings. Acta Radiol. 2013;54(10):1138–49.
7.Masuda T, et al. Follicular bronchiolitis associated with Legionella pneumophila infection. Pediatr Pathol Mol Med. 2002;21:41–47.
8.Romero S, et al. Follicular bronchiolitis: clinical and pathologic findings in six patients. Lung. 2003;181(6):309–19.
9.Koss MN, et al. Lymphoid interstitial pneumonia: clinicopathological and immunopathological findings in 18 cases. Pathology. 1987;19(2):178–85.
10.Pipavath SJ, et al. Radiologic and pathologic features of bronchiolitis. AJR Am J Roentgenol. 2005;185:354–63.
2019.12.18