Plastic Bronchitis: A Manifestation of Dander Hypersensitivity

clinical case letter

Indian Pediatr 2020;57: 760-761

Plastic Bronchitis: A Manifestation of Dander Hypersensitivity

Ritika Chhawchharia¹, Neeraj Gupta^1*, Dhiren Gupta¹ and Poojan Agarwal²

Departments of ¹Pediatric Pulmonology and Allergy, ²Pathology, Sir Ganga Ram Hospital, New Delhi, India.
Email: [email protected]

Plastic bronchitis, an entity with grave prognosis, is characterized by formation of large, branching bronchial casts obstructing the tracheobronchial tree. It has been previously reported in children with cyanotic congenital heart disease (CHD), asthma, allergic broncho-pulmonary aspergillosis (ABPA) and cystic fibrosis. A 9-month old boy presented with severe respiratory distress which required invasive ventilation for type-2 respiratory failure. He had received inhaled bronchodilators twice for recurrent cough in last 3 months. His grandfather had asthma and required inhaled medications. The child had exposure to animal dander (buffalo and cow) and wheat dust from nearby farm since birth. At admission, child had end-expiratory wheeze in left axillary area. High requirement of lung inflation pressures and loss of alpha-angle on end-tidal carbon dioxide graphic suggested obstructive airway. Salbutamol and ipratropium bromide nebulization along with systemic glucocorticoids partially reduced ventilatory requirements. Negative sepsis screen (CRP, procalcitonin, blood and tracheal culture) ruled out possibility of infection. Chest imaging (X-ray and CECT) suggested complete left lung collapse. Flexible bedside-bronchoscopy revealed thick, tenacious mucus plug, completely occluding the left main bronchus which could not be aspirated by multiple lavage attempts. A tree shaped, branching bronchial cast was removed from the left main bronchus via rigid bronchoscopy (Fig. 1a). Baby was weaned off from ventilator over next 24 hours. Nebulized 3% saline was used along with chest physiotherapy for pulmonary toileting. Charcot-Leyden crystals with eosinophils and polymorphs were demonstrated on cytopathological examination of broncho-alveolar lavage (BAL) (Fig. 1b). Cast histopathology showed eosinophils with necrotic background (type1 variety). Total immunoglobulin E (IgE) level was raised (276 IU/ml) with positive skin prick test (SPT) for buffalo dander. SPT for milk, egg, house dust, house dust mite, cow dander and wheat grass were negative. SPT was done with commercially available allergen extracts (Alcure Pharma) for local flora and fauna with valid positive and negative controls. Sweat chloride test and echocardiography was normal. The eczematous lesions over his back responded well to topical therapy. With a suggestive history of atopy, skin and respiratory manifestations, presence of Charcot Leyden crystals with eosinophils in cast and positive SPT for buffalo dander, an IgE-mediated allergic phenomenon was the most appropriate possibility. He was discharged on inhaled corticosteroids and oral montelukast with instructions to avoid buffalo dander, by shifting to maternal grandparents’ home, and an emergency action-plan. Inhaled steroids were tapered over next 9 months. The child remained asymptomatic at 1-year in follow-up on montelukast alone and allergen avoidance measures.

Fig.1 (a) Branching bronchial cast removed from left main bronchus; (b) red-colored diamond shaped Charcot-Leyden crystal (arrow) seen in the background of eosinophils and polymorphs in cytopathological examination of BAL fluid.

Plastic bronchitis is a rare disease, with unknown prevalence, characterized by formation of thick, cohesive casts leading to complete or partial occlusion of the airway. Type I casts have cellular infiltrates, fibrin and are primarily associated with pulmonary disease like asthma, cystic fibrosis and ABPA, while type II are acellular casts with, mucin and few mononuclear cells, mainly seen in cardiac conditions. It has been classified as per underlying etiology into mucinous (structural CHDs), chylous (lymphatic disorders), inflammatory (atopy-asthma), and fibrinous casts in sickle cell acute chest syndrome (SCACS) [1]. It has also been documented after Fontan procedure, probably due to maladaptation to cavo-pulmonary circulation [2]. Casts associated with atopy or asthma are described as inflammatory with eosinophils, Charcot Leyden crystals and occasional neutrophils in a fibrinous background [1]. While expectoration of thick, rubbery, branching casts is pathogmonic, patients usually present with cough, dyspnea or sometimes respiratory failure with suspicion of foreign body aspiration [3]. Management involves cast removal, chest physiotherapy, Dornase-a or hypertonic-saline or N-Acetylcysteine nebulization along with treatment of underlying disease [4]. With adequate supportive management, allergen identification and targeted measures (including immunotherapy) play an important role. Only one case of a 10-month infant with milk allergy and mucinous cast has been reported earlier [5].

Plastic bronchitis is one of the extreme presentations of allergic airway disorders. Animal dander exposure is common in developing world where increasing number of allergies are being recognized. The index case highlights the unique presentation of possible buffalo dander hypersensitivity in an atopic infant.

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