Article Text

The curious incident of the cast in the airway
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  1. Yueqi Ge1,
  2. Emily C Bartlett2,3,
  3. Thomas Semple2,3,
  4. Alexandra Rice4,
  5. Anand Shah1,5,
  6. Elisabetta A Renzoni1,3
  1. 1Respiratory Department, Royal Brompton Hospital, London, UK
  2. 2Radiology Department, Royal Brompton Hospital, London, UK
  3. 3National Heart and Lung Institute, Imperial College London, London, UK
  4. 4Histopathology Department, Royal Brompton Hospital, London, UK
  5. 5Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
  1. Correspondence to Dr Yueqi Ge, Respiratory Department, Royal Brompton Hospital, London SW3 6NP, UK; yueqi.ge{at}nhs.net

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Case presentation

A 52-year-old man presented with progressive dyspnoea and productive cough over 4 months. He was in type 2 respiratory failure (pO2 7.99 kPa/60 mm Hg; pCO2 9.32 kPa/70 mm Hg) with fluid overload and was started on non-invasive ventilation and intravenous diuresis in intensive care. Physical examination was significant for his short neck, small jaw and body mass index of 50. He was expectorating thick branching sputum, and bronchial casts were retrieved on bronchoscopy (figure 1A).

Figure 1

(A) Image of bronchial cast removed during bronchoscopy. (B) Section of laminated proteinaceous cast material (black arrow) with admixed small lymphocytes and foamy macrophages (black arrow) with scale bar (H&E ×40).

A chest CT showed endobronchial material and extensive bilateral ground glass opacification (figure 2A,B). Sputum cultures were negative but biochemical analysis revealed high triglycerides. Histopathological analysis revealed a fibrinous sample with foamy macrophages, occasional eosinophils and mildly atypical epithelioid cells (figure 1B). A thoracic CT lymphangiogram revealed retrograde pulmonary lymphatic perfusion of the right lung with intact left thoracic duct (figure 2C). An inguinal lymph node biopsy showed numerous vascular channels interspersed by hyaline fibrosis and lymphoid stroma. Genetic screening for inherited vasculopathies, primary lymphoedema and Noonan syndrome was negative.

Figure 2

(A, B) Coronal and axial CT imaging on admission demonstrating bronchial cast in the bronchus intermedius (black arrows) and diffuse ground glass opacification in the right lower, middle and upper lobes and left lower lobe. (C) CT lymphangiogram performed 3 weeks later demonstrating abnormal retrograde lymphatic drainage on the right (white arrow); the left thoracic duct is normal (see also online supplemental material). The contrast is a lymphatic sclerosant with therapeutic potential. (D) CT imaging 8 months after beginning treatment demonstrating almost complete resolution of ground glass opacities.

Based on bronchial cast expectoration, high sputum triglycerides and positive lymphangiography, lymphatic plastic bronchitis was diagnosed. A low medium-chain triglyceride diet, nebulised dornase-α, nebulised alteplase and subcutaneous octreotide were commenced. Sirolimus was subsequently added to good effect. Eight months following discharge, the patient reported no further expectoration of casts. A repeat CT (figure 2D) showed almost complete clearance of ground glass opacities.

Discussion

Lymphatic plastic bronchitis is a very rare pulmonary manifestation characterised by expectoration of branching rubbery casts of lymphatic material from the tracheobronchial airway.1 It is mostly seen in children following palliative cyanotic congenital heart surgery, owing to lymph leakage from elevated central venous pressures.2 In adults it can be associated with abnormal lymph flow, including primary (often genetically determined, such as in Noonan and Turner syndromes) or secondary lymphangiectasia, and lymphangiomatosis, characterised by abnormal proliferation of lymphatic channels.1 Additionally, morbid obesity may also be a significant risk factor.3 Other types of plastic bronchitis can be related to cardiac and sickle-cell disease.1 2 Lymphatic plastic bronchitis is clinically suspected on inspection of expectorated bronchial chylous casts, and diagnosis is established by dynamic magnetic resonance lymphangiography which reveals abnormal lymphatic flow. Treatment involves mechanical cast extraction via bronchoscopy and physical therapy. Chemical liquefaction using nebulised mucolytics and tissue plasminogen activators (t-PA) has demonstrated efficacy in vitro.2 Phase II trials are currently ongoing. Of note, t-PA can be associated with increased bleeding risk, currently being investigated in an open label trial (NCT02315898). Octreotide, a somatostatin analogue, is proposed to reduce chyle flow while sirolimus, a mechanistic target of rapamycin (mTOR) inhibitor, has shown therapeutic promise, presumably inhibiting proliferation of abnormal lymphatic channels,2 although their effectiveness remains undetermined due to the paucity of case reports. An open label trial of sirolimus treatment for lymphatic plastic bronchitis is currently recruiting (NCT03942926). As a single case the relative efficacy of each therapeutic modality is unclear, highlighting the need for prospective randomised controlled trials and international registry datasets in this rare disease.3 In adults, definitive treatment is through ablation of aberrant lymphatic channels using percutaneous image-guided embolisation or video-assisted thoracoscopic ligation of the thoracic duct. This case highlights the importance of lymphangiography in establishing aberrant lymphatic flow and directing definitive management.

References

Supplementary materials

  • Supplementary Data

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Footnotes

  • Twitter @drAnand_Shah_

  • Contributors YG drafted the manuscript. ECB and TS provided radiological input. AR provided histopathological analysis. EAR and AS revised the manuscript and all authors assisted in the editorial process.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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