Surviving laryngotracheal mucormycosis: conquering central airway challenges

Laryngotracheal mucormycosis presents a rare but critical challenge, particularly in immunocompromised individuals. This report details the case of a 31-year-old diabetic male who experienced central airway obstruction due to mucor-mycosis. Despite the complexity of managing airway involvement, a multidisciplinary approach involving airway debridement surgery, liposomal amphotericin B, and posaconazole resulted in successful airway mucor treatment and resolution. This case underscores the importance of early recognition, aggressive intervention, and collaborative care in managing life-threatening conditions.


Introduction
Mucormycosis is caused by a fungus that belongs to the order Mucorales [1].It most commonly affects the sinuses or the lungs after inhaling fungal spores from the air.The most common risk factors are hematologic malignancies, diabetes mellitus, organ transplantation, bone marrow aplasia, COPD on chronic steroid, and deferoxamine therapy for iron overload.Typically, pulmonary involvement manifests as cavitary pneumonia with concurrent involvement of adjacent bronchi.Rarely, patients may present with exclusive central airway involvement, affecting the larynx and/or trachea without any associated parenchymal disease.
Diagnosing such a condition poses significant challenges due to the difficulty of obtaining a biopsy from the central airway.The prognosis is often unfavorable, as surgical intervention may not be feasible.The present report describes a rare manifestation of the disease in a young diabetic patient with isolated laryngotracheal mucormycosis who was treated with airway debridement surgery, liposomal amphotericin B (AMB), and posaconazole.

Case report
A 31-year-old male with poorly controlled diabetes mellitus presented to the emergency with hoarseness of voice and stridor for 15 days, gradually progressive breathlessness for six weeks, and weight loss of 15 kg over a period of last 2-3 months.On examination, the patient was having a stridor on deep breathing.The systemic evaluation, encompassing examinations of the eye, upper as well as lower respiratory tract, and central nervous system, was normal.Computed tomography (CT) of the neck and thorax showed subglottic tracheal stenosis with left-sided eccentric thickening (measuring 22 × 12 mm), while mediastinum, bronchial tree, lung vasculature, and parenchyma were normal in appearance.CT brain and paranasal sinus was also done, and the possibility of rhinocerebral involvement was ruled out.Under general anesthesia, flexible bronchoscopy was done, which showed circumferential fungating slough at the bilateral vocal cord and subglottic level, causing 30-40% narrowing of the tracheal lumen involving two tracheal rings (Fig. 1).Multiple biopsies were taken from the fungating slough.The rest of the tracheal area and bilateral bronchial tree were normal.Histopathological examination showed abundant necro-inflammatory exudate with broad aseptate irregular folded fungal hyphae, establishing the diagnosis of mucormycosis.The patient was started on liposomal amphotericin B and oral posaconazole with strict glycemic control under insulin.The otolaryngology team was involved, and the patient underwent extensive laryngotracheal debridement.Resection surgery was deemed unfeasible due to the extensive involvement of the trachea.The patient had a good clinical and radiological response to the given treatment.A repeat flexible bronchoscopy, conducted 10 weeks after debridement and continuous dual antifungal treatment, revealed complete resolution of the airway mucor, leaving behind tracheal stenosis (Fig. 1).CT neck also did not show any residual disease.

Discussion
Mucormycosis is a life-threatening, opportunistic tissue and angio-invasive disease.The disease can manifest as rhino-cerebral, pulmonary, gastrointestinal, cutaneous, and disseminated infection.Out of which, rhino cerebral is the most common form, whereas cutaneous manifestations are the most common presentations in trauma patients.In a review by Baker of 116 cases, 16% were cutaneous, 39% were rhino cerebral, 22% were pulmonary, 16% were disseminated, and 4% were gastrointestinal [1].
Isolated central airway involvement in mucormycosis is rare.In the literature, less than 10 cases of tracheal, laryngeal, and laryngotracheal mucormycosis have been reported, and uncontrolled diabetes state was the risk factor in the majority of the cases [4][5][6][7][8][9][10][11][12][13][14][15][16][17]18].The reported common clinical symptoms were sore throat, progressive hoarseness, and dysphagia; our patient presented with hoarseness and weight loss [4,[6][7][8]10] .In our case, the significant potential differential diagnoses were granulomatous diseases like tuberculosis and neoplastic diseases such as infiltrating lymphoproliferative disease and adenoid cystic carcinoma.Additionally, infectious causes, apart from tuberculosis, could involve invasive mycotic diseases, although instances of aspergillosis and mucormycosis are rare [17] .In such cases, a crucial diagnostic step consists in obtaining a biopsy of the lesion, as sampling from a tracheal lesion could potentially result in massive bleeding into the central airway, so if the lesion bleeds just on touch, one should consider rigid bronchoscopic sampling.In our cases, bleeding was not reported, so we were able to take a biopsy with a flexible bronchoscope.
Surgical interventions, encompassing debridement, repair, and resection with anastomosis, combined with antifungal therapy, have remained central to the treatment in most cases reviewed [6,7,9,[13][14][15] .Liposomal AmB is the preferred initial therapy.Following an initial 2-6-week course of amphotericin B, patients may transition to posaconazole or isavuconazole for maintenance antifungal treatment.The recommended amphotericin (liposomal) dose is 3-10 mg/kg/day.We used 5 mg/kg/ day along with oral posaconazole.Among the very few cases of central airway mucor, the usual strategy is to debride the infective area along with liposomal AMB therapy [10,12,14,16] .Due to the rarity of central airway mucormycosis, detailed literature is insufficient to recommend any specific surgical treatment modality.Local site debridement, dilatation, and resection anastomosis surgeries have yielded promising results (Table 1).In our case, extensive laryngotracheal debridement was performed using a tracheostomy in collaboration with the head and neck onco-surgeon's team.A basic understanding of central airway obstruction (CAO) management is the standard for such mucor cases, and if the area involved is amenable to surgery, one should consider resection anastomosis surgery.If resection surgery is planned, it is typically conducted after 2-4 weeks; once the fungal burden is reduced, so airway anastomosis occurs smoothly without any leakage [4] .Although because of the paucity of cases, there is no clear understanding of the intervention time.In life-threatening central airway obstruction, airway stents may be introduced to the trachea or tracheobronchial tree to recanalize the central airway [17].

Conclusion
Isolated laryngotracheal mucormycosis is a rarely reported entity.General principles of mucormycosis management and central airway management strategy should be followed to achieve favorable outcomes.Such cases should be approached by a multidisciplinary team comprising an interventional pulmonologist, a neck surgeon, and an infectious disease specialist.

Table 1
Review of surgically managed cases of central airway mucormycosis