Medical Image of the Week: Plastic Bronchitis in an Adult Lung Transplant Patient

Figure 1. Representative coronal (A) and axial (B) views of the thoracic CT scan in lung windows revealing bilateral dense consolidations and bronchial filling.

Figure 2. Photograph of bronchial gelatinous casts after bronchoscopic forceps removal.

Plastic Bronchitis is a rare condition characterized by the formation of branching gelatinous casts of the bronchial tree which lead to regional airway obstruction. There are thought to be two classifications of casts; type I being the formation of cellular inflammatory casts while type II are acellular. This entity is a well described complication of the Fontan procedure, a therapeutic intervention in pediatric patients with univentricular congenital heart disease (1). The condition is less well reported and thus recognized in adult populations (2).

Our patient is a 37-year-old man who is status post bilateral lung transplantation undertaken for severe workplace inhalation injury complicated by constrictive bronchiolitis-obliterans. Post-transplant, the patient suffered from refractory severe persistent asthma of the donor lung and therefore was scheduled for elective initial bronchial thermoplasty. Post-procedure the patient developed progressive respiratory distress and ultimately extremis requiring mechanical ventilation. Pulse-dose corticosteroids were initiated given a suspected etiology of acute rejection, although response to therapy was poor. Bronchoscopy was conducted which revealed diffuse fibrin casts of the right lung consistent with the development of plastic bronchitis. Symptoms significantly improved with removal of these casts, although a repeat bronchoscopy with cast removal was necessary shortly afterward. Our patient’s cast formation is unique given that it likely has components of both etiologies given his underlying bronchial hyper-secretory disorder and lymphatic disruption after lung transplant. For this reason, we consider this a unique case in its ability to highlight the overlap of these two pathologic processes in an otherwise unlikely demographic to develop bronchial casts. In our comprehensive literature search, we were unable to find significant description of this disorder in adult lung transplant. However, given the disruption in lymphatics, host vs graft inflammatory factors, and infectious inflammatory factors, it would seem to be a perfect setup pathologically. The underlying pathophysiologic mechanism of plastic bronchitis is believed to be cast formation via pulmonary lymphatic disruption by either surgical intervention or inflammatory processes. Gelatinous casts are formed by way of alveolar capillary leak of proteinaceous material, lymphatic seepage, and exudate accumulation from airway inflammation. The majority of literature regarding this disease processes has been described in pediatric thoracic surgery. Lung transplant, especially in the setting of acute rejection, seems to be a setup for this condition in adult populations.

Sarika Savajiyani DO, Nafis Shamsid-Deen MD, and  Raed Alalawi MD

University of Arizona, College of Medicine-Phoenix

Phoenix, AZ USA

References

1. Singhi AK, Vinoth B, Kuruvilla S, Sivakumar K. Plastic bronchitis. Ann Pediatr Cardiol. 2015 Sep-Dec;8(3):246-8. [CrossRef] [PubMed]
2. Eberlein M, Parekh K, Hansdottir S, Keech J, Klesney-Tait J. Plastic bronchitis complicating primary graft dysfunction after lung transplantation. Ann Thorac Surg. 2014 Nov;98(5):1849. [CrossRef]

Cite as: Savajiyani S, Shamsid-Deen N, Alalawi R. Medical image of the week: Plastic bronchitis in an adult lung transplant patient. Southwest J Pulm Crit Care. 2018;17(1):39-40. doi: https://doi.org/10.13175/swjpcc088-18 PDF 

Medical Image of the Week: Methemoglobinemia

Figure 1. A: cyanotic lips and tongue. B: restoration of reddish color after methylene blue infusion.

Figure 2. Patient’s blood showing a chocolate brown color.

A 62-year-old man with a sternal infection post-coronary artery bypass grafting was transferred because of increasing oxygen requirements, decreased mental status and Candida paralopsis fungemia. He had been treated with multiple antibiotics including sulfonamides and had eventually undergone a tracheostomy. Cetacaine was used for complaints of a sore throat. Physical examination showed cyanotic lips and tongue (Figure 1A). Blood drawn was a chocolate brown color (Figure 2). His SpO2 was 88%, however, arterial blood gases showed his SaO2 was 100% and his PaO2 453 mmHg. Co-oximetry showed 26% methemoglobin. He was administered 0.2mL/kg of 1% solution of methylene blue and his cyanosis rapidly cleared (Figure 1B).

Methemoglobinemia is a condition characterized by increased quantities of hemoglobin with iron oxidized to the ferric (Fe3+) form (1). Methemoglobin is useless as an oxygen carrier and thus causes a varying degree of cyanosis and hypoxia. It can be genetic but is usually caused by exposure to drugs or toxins. Symptoms are proportional to the fraction of methemoglobin. A normal methemoglobin fraction is about 1%. Symptoms associated with higher levels of methemoglobin are: 3-15% - cyanosis; 25-50% - headache, dyspnea; 50-70% - cardiac arrhythmias, altered mental status, delirium, seizures, coma; >70% - death. Drugs most commonly associated with methemoglobinemia include topical and injected local anesthetics (benzocaine, lidocaine, cetacaine), sulfonamides (dapsone), and nitrates (nitroprusside).

Intravenous methylene blue, a reducing agent, is the traditional antidotal agent (1). Exchange transfusion and hyperbaric oxygen treatment are second-line options for patients with severe methemoglobinemia who do not respond to methylene blue or who cannot be treated with methylene blue (e.g., those with glucose-6-phosphate dehydrogenase [G6PD] deficiency).

Robert A. Raschke, MD, MS

University of Arizona College of Medicine-Phoenix and Banner University Medical Center

Phoenix, AZ USA

Reference

1. Denshaw-Burke M. Methemoglobinemia. Medscape. Nov 14, 2017. Available at: https://emedicine.medscape.com/article/204178-overview (accessed 1/11/18).

Cite as: Raschke RA. Medical image of the week: methemoglobinemia. Southwest J Pulm Crit Care. 2018;16(1):49-50. doi: https://doi.org/10.13175/swjpcc007-18 PDF