An 8-year-old, Patterdale terrier was referred for evaluation of tachypnoea, exercise intolerance, and weight loss. Computed tomographic images showed pneumomediastinum, diffuse pulmonary ground glass opacity, and marked dilatation of peripheral bronchi, but no evidence of thickened bronchial walls. The histopathologic diagnosis was diffuse pulmonary interstitial fibrosis, type II pneumocyte hyperplasia, and bronchiectasis. The lack of evidence of primary bronchitis supported a diagnosis of traction bronchiectasis. Traction bronchiectasis can occur as a sequela to pulmonary fibrosis in dogs. (C) 2016 American College of Veterinary Radiology

Fitzgerald, E

Lamb, C R

Priestnall, S L

English

RVC Research Online

  RVC OPEN ACCESS REPOSITORY – COPYRIGHT NOTICE  This is the peer reviewed version of the following article: Fitzgerald, E., Priestnall, S. L. and Lamb, C. R. (2016), IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHY OF TRACTION BRONCHIECTASIS SECONDARY TO PULMONARY FIBROSIS IN A PATTERDALE TERRIER. Veterinary Radiology & Ultrasound. doi:10.1111/vru.12403 which has been published in final form at http://dx.doi.org/10.1111/vru.12403.         This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. The full details of the published version of the article are as follows:  TITLE: IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHY OF TRACTION BRONCHIECTASIS SECONDARY TO PULMONARY FIBROSIS IN A PATTERDALE TERRIER AUTHORS: Fitzgerald, E., Priestnall, S. L. and Lamb, C. R.  JOURNAL TITLE: Veterinary Radiology & Ultrasound PUBLISHER: Wiley PUBLICATION DATE: July 2016 (online) DOI: 10.1111/vru.12403  1  Imaging diagnosis 1 Computed tomography of traction bronchiectasis secondary to pulmonary 2 fibrosis in a Patterdale terrier 3 Ella Fitzgerald, Simon L. Priestnall, Christopher R. Lamb 4 The Royal Veterinary College, University of London 5  6 Address correspondence to: C.R. Lamb, Department of Clinical Sciences and 7 Services, The Royal Veterinary College, Hawkshead Lane, North Mymms, 8 Hertfordshire AL9 7TA, UK  9  10 Abstract 11 An 8-year-old, Patterdale terrier was referred for evaluation of tachypnoea, exercise 12 intolerance, and weight loss. Computed tomographic images showed 13 pneumomediastinum, diffuse ground glass opacity, and marked dilatation of 14 peripheral bronchi, but no thickened bronchial walls. The histopathologic diagnosis 15 was diffuse pulmonary interstitial fibrosis, type II pneumocyte hyperplasia, and 16 bronchiectasis. The lack of evidence of primary bronchitis supports a diagnosis of 17 traction bronchiectasis. Traction bronchiectasis can occur as a sequela to pulmonary 18 fibrosis in dogs.  19 Key words: computed tomography, dog, pneumomediastinum, pulmonary fibrosis, 20 traction bronchiectasis 21 Running head: Traction bronchiectasis in a Patterdale terrier  22 2  Signalment, history and clinical findings 23 An 8-year-old female neutered Patterdale terrier had worsening tachypnoea, 24 exercise intolerance and weight loss over a period of 4 months. A short course of 25 broad-spectrum antibiotics and anti-inflammatory drugs had no apparent effect on 26 clinical signs. At referral, there was marked tachypnea (120 breaths per minute) and 27 inspiratory dyspnea. No abnormal breath sounds were identified on auscultation. 28 Mucous membranes were slightly tacky with a normal capillary refill time.  29 Cardiovascular evaluation was unremarkable and body temperature was normal 30 (38°C). Body condition score was 3/9. Haematological and biochemical evaluation 31 revealed slightly increased urea, creatinine, creatine kinase and total protein. 32 Echocardiography revealed no abnormalities. Blood antigen test for canine 33 lungworm (Angiostrongylus vasorum) was negative. Shortly after arrival, the patient’s 34 respiratory rate and effort increased. The dog became hypoxic and was placed in an 35 oxygen chamber.  36  37 Imaging diagnosis and outcome 38 Thoracic radiography at the primary care practice 3 months prior to referral found a 39 pneumomediastinum and diffuse, unstructured interstitial pattern affecting all lung 40 lobes. To further characterize the pulmonary changes computed tomography (CT) of 41 the thorax was performed using a 16-slice scanner (Mx8000 IDT, Philips, Best, The 42 Netherlands) with the dog in ventral recumbency under general anesthesia. The CT 43 settings were 120 kVp, 150 mA, 16 x 1.5 mm collimation, pitch 1, tube rotation time 44 0.5s, and 3mm reconstruction slice thickness. Images were reconstructed using 45 medium and high frequency algorithms. Images were acquired pre- and post-46 3  intravenous bolus injection of contrast medium at 600mgI/kg body weight 47 (Omnipaque, iohexol, 300 mg I/mL, GE Healthcare AS, Nycoveie 1–2, NO-0401 48 Oslo, Norway). There was a large volume pneumomediastinum and diffuse, uniform 49 pulmonary ground-glass opacity (700HU), and a lack of normal tapering and 50 dilatation of the peripheral bronchi, but no apparent thickening of the bronchial walls 51 (Fig. 1).  52 Dilatation of the peripheral bronchi was considered to be the major finding, indicative 53 of bronchiectasis, whereas pneumomediastinum and pulmonary ground-glass 54 attenuation were non-specific findings. Differential diagnoses for bronchiectasis 55 include primary bronchial disease (i.e. chronic bronchitis) or traction bronchiectasis 56 secondary to pulmonary fibrosis. The history, clinical signs, and lack of bronchial wall 57 thickening supported the latter diagnosis. 58 A post-CT bronchoalveolar lavage revealed a mild neutrophilic inflammation. No 59 bacterial growth was noted after four days of incubation and further culture for 60 Mycoplasma spp. was negative. A short trial of systemic steroids and inhaled 61 bronchodilator (Salbutamol) was initiated, and the dog continued to receive 62 supplemental oxygen; however, signs continued to worsen with increasing 63 respiratory rate and effort. The dog was euthanized at the owners’ request. 64 At necropsy, there was pneumomediastinum and the lungs were firm and diffusely 65 pale. Multiple small (<2mm diameter) raised foci were noted on the visceral pleural 66 surface, which was thickened and had a wrinkled contour. Histologic examination of 67 the lung found marked thickening of the alveolar septa and subpleural space with 68 fibrous connective tissue. Multiple alveoli were lined by plump cuboidal cells 69 consistent with type II pneumocyte hyperplasia. In addition, the alveolar spaces 70 contained proteinaecous material, foamy macrophages and multinucleate 71 4  hemosiderin-containing cells (hemosiderophages). Markedly dilated terminal 72 bronchioles were identified adjacent to the pleural surface (Fig. 2). The histologic 73 diagnosis was marked, diffuse, chronic interstitial fibrosis and chronic-active 74 alveolitis with secondary traction bronchiectasis.  75  76 Discussion 77 Traction bronchiectasis is an irreversible dilation of the bronchioles that occurs 78 secondary to pulmonary fibrosis.1 In humans, it is often associated with end-stage 79 lung disease but has also been identified with other chronic lung diseases.2 Three 80 mechanisms of bronchial dilation have been described: damage to the bronchial 81 wall, obstruction of the lumen, and traction from surrounding fibrotic tissue.2 Damage 82 to the bronchial wall is usually secondary to infection and the associated 83 inflammatory response with release of inflammatory mediators including neutrophil 84 elastases, which degrade mural connective tissue. In chronic bronchitis, thickening 85 of bronchial walls, dilatation of bronchi, and mucus plugging the bronchial lumen may 86 be observed. In traction bronchiectasis, tension arising from contraction of 87 surrounding fibrous tissue dilates the bronchial lumen without other signs of 88 bronchial disease. In each form of bronchiectasis, there is chronic irreversible 89 damage to the supportive connective tissue within the bronchial and bronchiolar 90 wall.2  91 The term “honeycombing” has been associated end-stage interstitial lung fibrosis 92 and describes clusters of subpleural cystic airspaces. Histologically, there is 93 complete loss of acinar architexture.3 In the present case, there was intervening lung 94 5  between dilated airspaces, hence it would be incorrect to use the term 95 “honeycombing”.4 96 Traction bronchiectasis has been reported as a sequela to pulmonary fibrosis in 97 dogs5, but not illustrated. Ante mortem diagnosis of pulmonary fibrosis is difficult and 98 relies on exclusion of other types of infiltrative disease such as interstitial 99 pneumonia, neoplasia, and non-cardiogenic edema. Definitive diagnosis depends on 100 lung biopsy, which is an invasive procedure with significant morbidity.6 In humans, 101 CT findings alone can now be used to diagnose idiopathic pulmonary fibrosis without 102 the need for tissue confirmation.7 Traction bronchiectasis is a key criterion for CT 103 diagnosis of pulmonary fibrosis in humans.7 Increasing severity of traction 104 bronchiectasis correlates with a poorer prognosis in humans.8 However such a 105 correlation has not been made in veterinary medicine. In the present case, the CT 106 finding of peripheral bronchiectasis was an important sign of pulmonary fibrosis. 107 Pneumomediastinum (and pneumothorax) have been observed in dogs with 108 bronchiectasis.9 In these cases, air leaks through sites of alveolar rupture, tracks 109 along the bronchovascular interstitium and accumulates within the mediastinum. This 110 is the Macklin effect.10 The specific site of air leak causing pneumomediastinum was 111 not identified in the present case. It is possible that a sudden increase in the volume 112 of mediastinal air in this patient may account for the acute respiratory 113 decompensation following admission.   114 6  References 115 1. Westcott JL, Cole SR. Traction bronchiectasis in end-stage pulmonary fibrosis. 116 Radiology. 1986;161:665–9.  117 2. Javidan-Nejad C, Bhalla S. Bronchiectasis. Radiol Clin North Am. 2009;47:289–118 306.  119 3. Hansell DM, Bankier AA, MacMahon H, McLoud TC, Müller NL, Remy J. 120 Fleischner Society: glossary of terms for thoracic imaging. Radiology. 121 2008;246:697–722. 122 4. Arakawa H, Honma K. Honeycomb lung: history and current concepts. Am J 123 Roentgenol. 2011; 196:773–82. 124 5. Heikkilä HP, Lappalainen AK, Day MJ, Clercx C, Rajamäki MM. Clinical, 125 Bronchoscopic, Histopathologic, Diagnostic Imaging, and Arterial Oxygenation 126 Findings in West Highland White Terriers with Idiopathic Pulmonary Fibrosis. J 127 Vet Intern Med. 2011;25:433–9.  128 6. Zekas LJ, Crawford JT, O'Brien RT. Computed Tomgraphy-guided fine aspirate 129 and tissue-core biopsy of intrathoracic lesions in thirty dogs and cats. Vet Radiol 130 Ultrasound. 2005;46:200–4.  131 7. Gruden JF. CT in Idiopathic Pulmonary Fibrosis: Diagnosis and Beyond. Am J 132 Roentgenol 2016;206:495–507.  133 8. Edey AJ, Devaraj AA, Barker RP, Nicholson AG, Wells AU, Hansell DM. Fibrotic 134 idiopathic interstitial pneumonias: HRCT findings that predict mortality. Eur 135 Radiol 2011;21:1586–93. 136 7  9. Johnson LR, Johnson EG, Vernau W, KASS PH, Byrne BA. Bronchoscopy, 137 Imaging, and Concurrent Diseases in Dogs with Bronchiectasis: (2003-2014). J 138 Vet Intern Med 2016;30:247–54.  139 10.  Macklin MT, Macklin CC. Malignant interstitial emphysema of the lungs and 140 mediastinum as an important occult complication in many respiratory diseases 141 and other conditions: interpretation of the clinical literature in the light of 142 laboratory experiment. Medicine 1944;23:281–358. 143  144 List of Author Contributions 145 Category 1 146 (a) Conception and Design 147 Author name (s) Ella Fitzgerald, Simon L. Priestnall, Christopher R. Lamb 148 (b) Acquisition of Data 149 Author name (s) Ella Fitzgerald, Simon L. Priestnall, Christopher R. Lamb 150 (c) Analysis and Interpretation of Data 151 Author name (s) Ella Fitzgerald, Simon L. Priestnall, Christopher R. Lamb 152   153 Category 2 154 (a) Drafting the Article 155 Author name (s) Ella Fitzgerald, Simon L. Priestnall, Christopher R. Lamb 156 (b) Revising Article for Intellectual Content 157 Author name (s) Ella Fitzgerald, Simon L. Priestnall, Christopher R. Lamb 158   159 Category 3 160 8  (a) Final Approval of the Completed Article 161 Author name(s) Ella Fitzgerald, Simon L. Priestnall, Christopher R. Lamb 162   163 9  Legends 164 Figure 1. Transverse (A) and oblique (B) CT images of the thorax showing 165 pneumomediastinum (*), diffuse ground glass pulmonary opacity, and uneven 166 dilation of the peripheral bronchi in left caudal lobe (arrowheads) and accessory lobe 167 (arrow) compatible with bronchiectasis.  168  169   170 10  Figure 2. Hematoxylin and eosin-stained histologic sections of lung (A, x20 171 magnification) and (B, x20 magnification) showing a dilated bronchioles (B).  The 172 visceral pleural surface of the lung (arrowheads) appears normal, but there is 173 marked fibrosis of the subpleural parenchyma (F). There is a lack of abnormalities 174 affecting the respiratory epithelium of the small bronchiole (arrow). Bar = 1.5 mm 175  176 

Imaging diagnosis-computed tomography of traction bronchiectasis secondary to pulmonary fibrosis in a Patterdale Terrier

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Imaging diagnosis-computed tomography of traction bronchiectasis secondary to pulmonary fibrosis in a Patterdale Terrier

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