Tracheobronchial rhinosporidiosis: an uncommon life‐threatening benign cause of airway obstruction

Abstract Rhinosporidiosis is a chronic granulomatous infectious disease caused by Mesomycetozoea Rhinosporidium seeberi. This highly recurrent polypoid lesion has a predilection for the nose and nasopharynx, although other organ systems may be affected. Involvement of the tracheobronchial tree is very rare, and poses a challenge for diagnosis and management. In this report, we present a 30‐year‐old man with a history of recurrent nasal polyp who presented with cough, shortness of breath, haemoptysis, and a radiological feature of right lung collapse on imaging. He was diagnosed with rhinosporidiosis based on histopathological examination of bronchoscopic biopsy specimen taken from the right principal bronchial mass. Shortly after hospitalization, he developed acute respiratory distress requiring emergency bronchoscopic intervention. A pinkish mulberry‐like tracheal and right bronchial mass was removed endoscopically with cauterization of the base of the lesion. On long‐term follow‐up, the patient was free of symptoms without recurrence of airway disease.


Introduction
Rhinosporidiosis is a chronic granulomatous infectious disease that manifests as a slow-growing tumour-like mass, commonly involving the nose and nasopharynx. The tracheobronchial tree is a very unusual site and poses challenge in management owing to recurrent nature of the disease. Here, we report the case of a patient with a previous history of recurrent nasal mass and multiple nasal surgeries, presented with right upper lobe collapse followed by sudden respiratory distress. Emergency bronchoscopic intervention was life-saving.

Case Report
A 30-year-old male from a rural background presented to a primary care physician with persistent cough and occasional sputum for six months and was getting treatment accordingly without much improvement. Four months later, he noticed frequent scanty haemoptysis and exertional breathlessness. There was no fever, wheeze, chest pain, and anorexia or weight loss. He was seen by a pulmonologist, and a routine chest X-ray showed right upper lobe collapse (Fig. 1A). Pulmonary tuberculosis was excluded after obtaining a negative report of sputum for acid-fast bacilli and GeneXpert (Cepheid, Inc., USA). A right principal bronchial mass was observed on flexible bronchoscopic examination, and histopathology revealed rhinosporidiosis. He was referred to our institute.
On admission, he was dyspnoeic with absence of breath sound in the right lung and poor air entry in the left lung. Oxygen saturation (SpO 2 ) breathing room air measured 89%. A computed tomography scan of the chest showed a polypoid mass in the right principal bronchus, extending up to the main carina (Fig. 1B). The patient was a farmer who frequently entered local pond water whilst fishing. His history included two previous operations five and eight years prior for management of a nasal mass. However, documentation from these procedures was not available. None of his family members reported such a disease. On the second day of admission, he developed sudden respiratory distress with a fall in SpO 2 to 72%. Hypoxaemia could not be corrected with 10 L/min supplemental oxygen via a partial rebreathing mask. Emergency rigid bronchoscopy (Karl Storz, Germany) was performed. A mulberry-like mass was seen nearly occluding the lower tracheal lumen. The mass was removed as much as possible by grasping forceps (Fig. 2), and bleeding was secured by applying pressure with adrenaline-soaked gauze. The post-operative period was uneventful. Microscopic examination of the resected specimen showed tissues lined by stratified squamous epithelium. The subepithelial stroma revealed the spherules of Rhinosporidium seeberi containing endospores.
One week later, fibreoptic bronchoscopy (FB) showed complete clearance of the tracheal lumen and a residual lesion in the proximal right principal bronchus and a mass hanging from the posterior nasopharyngeal wall (Fig. 3A, B). The rest of the bronchial tree in both lungs was free from any lesion. Rigid bronchoscopy was repeated after seven days to remove the residual lesion of the right bronchus with electrocauterization of the lesional base to prevent recurrence. Dapsone was started at 100 mg/day, and the patient was discharged with advice of monthly followup. Follow-up bronchoscopy was performed one and a half months later, which showed clearance of the bronchial lesion ( Fig. 3C) and regression of the nasopharyngeal mass (Fig. 4A). He continued medication for one year and then stopped by himself. Bronchoscopic evaluation two years later showed airway lumen free of any disease but a recurrent lesion on the left pharyngeal wall (Fig. 4B). Dapsone was started again, and he was referred for otorhinolaryngologist's consultation. At his last visit, he had no respiratory complaint, but there was nasal blockage.

Discussion
In 1892, Malbran, and later in 1896, Seeber described an apparent sporozoan parasite in nasal polyp in patients living in Buenos Aires, Argentina. In 1923, Ashworth described the life cycle of the organism, argued it as a fungus, and named it R. seeberi. Recent phylogenetic analysis suggests that it is a protistan organism in the newly described class Mesomycetozoea of animal-fungus boundary. Its natural host and reservoir are unknown [1,2]. The disease is reported in the United States, South America, Europe, Africa, and Asia, but most common in the tropics, with highest prevalence in Southern India and Sri Lanka [1]. Although detailed data are not available, the disease is not uncommon in Bangladesh.
Rhinosporidium seeberi has an affinity for the mucus membrane of the nasal cavity and nasopharynx. Various other sites may be involved, including the conjunctiva,    Table 1). The exact mode of infection is still unknown, but transepithelial transmission has been proposed as a probable mode of infection in natural aquatic environment, and there is a strong relationship between bathing in pond water and getting the disease. In their study, Karthikeyan et al. observed that 59.38% of patients with rhinosporidiosis had a history of bathing in ponds [4]. Organism may be implanted in the lower respiratory tract due to autoinoculation or haematogenous spread [18]. It is obvious that bronchial involvement in our patient was due to the implantation of the parasite from the nose during the previous surgery. The disease appears to be much more common in men than in women from a rural background and low socioeconomic status [4].
Patients may present with cough, wheeze, breathlessness, stridor, haemoptysis, or collapsed lung. If there is critical airway narrowing, there may be rapidly developing respiratory distress and even sudden death [5,6]. Acute hypoxaemia in our patient was likely due to the rapidly growing bronchial mass extending and occluding the lower trachea, compromising both lungs. Flexible bronchoscopy   is a useful tool for the diagnosis, evaluation, and management of tracheobronchial lesions, but caution should be exercised during biopsy, as there is a high risk of bleeding. Computed tomography imaging of the chest and virtual bronchoscopy may provide better details about the extent of the lesion [3]. Various methods have been used in management, including flexible and rigid bronchoscopic snaring, argon plasma coagulation, laser, tracheotomy, tracheostomy, and surgical excision. As our patient developed critical airway obstruction and acute hypoxaemia, we performed emergency rigid bronchoscopy and gently extracted the lesion using forceps, ensuring good haemostasis, and following a certain interval, repeated the procedure and cauterized the base to prevent recurrence. Dapsone (4, 4-diaminodiphenyl sulphone) was added to treat concomitant nasopharyngeal lesions and to prevent recurrence, which acts by arresting the maturation of sporangia and fibrosis of stroma [19]. The chance of recurrence of nasal rhinosporidiosis is 10%, but that of tracheobronchial lesions is unknown [3].
This challenging case rapidly developed critical central airway obstruction requiring immediate multidisciplinary planning to rescue the airway. Teamwork of interventional pulmonologists, thoracic surgeons, and anaesthesiologists led to a favourable outcome of the uncommon lifethreatening cause of airway obstruction.

Disclosure Statements
Appropriate written informed consent was obtained for publication of this case report and accompanying images. This case was presented at the 22nd Congress of the Asian Pacific Society of Respirology.