Abstract
Pulmonary mucormycosis is a life-threatening infection caused by a fungus that is part of the Mucorales family. Diabetes ketoacidosis has been classically described as the main risk factor for the disease. Tracheobronchial mucormycosis is an infrequent form of pulmonary mucormycosis that presents as a tracheobronchial tumor obstructing the airway. Few cases have been reported in the literature. We present a case of pulmonary mucormycosis that presented initially as a collapsed right upper lung, mimicking a tracheobronchial tumor. Early detection and treatment are key to avoid fatal outcomes.
Keywords: Mold, pulmonary mucormycosis, tracheobronchial mucormycosis, tracheobronchial tumor
Mucormycosis is an aggressive fatal fungal infection associated with high morbidity and mortality. There are well established risk factors, such as immunosuppression, poorly controlled diabetes mellitus, and hematological malignancies.1 Classically, the paranasal sinuses, orbits, cerebrum, and lungs are the most common initial focus of infection. Pulmonary mucormycosis recognition is challenging because it can either present clinically as pneumonia or grow as a tracheobronchial mass mimicking a bronchial malignancy.2,3 We present an uncommon presentation of indolent mucormycosis mimicking a tracheobronchial tumor.
CASE PRESENTATION
A 56-year-old woman was admitted with diabetes ketoacidosis due to insulin nonadherence. She also reported low-grade fevers, dyspnea, right subclavicular chest pain radiating toward her neck, and intermittent epistaxis with questionable hemoptysis for 6 weeks. On admission to the intensive care unit, her hemoglobin was 14.5 g/dL, white blood cells, 14.49 K/μL; total protein, 6.4 g/dL; albumin, 3.9 g/dL; and hemoglobin A1C, 15.5%. The right upper chest was tender to palpation with decreased air entry on auscultation. Chest imaging suggested a complete collapse of the right upper lobe and showed small mediastinal lymph nodes concerning for malignancy (Figure 1a, 1b). Bronchoscopy showed an erythematous, fungating endobronchial mass obstructing the right upper lobe entry concerning for malignancy (Figure 2a). Endobronchial ultrasound with fine-needle aspiration of lymph nodes was negative for malignancy. Biopsy of the mass showed broad irregular hyphae consistent with mucormycosis (Figure 2b). Blood, sputum, and bronchial aspirate cultures were all negative throughout her hospital stay. Computed tomography (CT) of the head, sinuses, and neck was unremarkable.
Figure 1.
Radiologic images. (a) Chest x-ray showing dense right upper lobe consolidation. (b) Chest CT showing collapse of the right upper lobe. (c) Chest CT at 3-month follow-up showing near complete resolution of the right upper lobe opacity with minimal residual atelectasis.
Figure 2.
Direct bronchoscopy and lesion biopsy. (a) Bronchoscopy showing a fungating bronchial mass suspicious for malignancy. (b) Histopathology smear showing broad irregular hyphae consistent with Mucor (red arrows).
The infectious disease team initially started the patient on intravenous liposomal amphotericin B with good response and resolution of symptoms. She was then switched to oral isavuconazole as a step-down therapy. Our cardiothoracic surgery team recommended against surgery due to her improvement on antifungal therapy as well as to avoid the risk of spreading Mucor to the pleural space with possible fatal consequences after lobectomy. The patient continued to improve and was discharged on 6 months of isavuconazole. She had near complete resolution of the right upper lobe opacity on chest CT at her 3-month follow-up visit (Figure 1c).
DISCUSSION
Tracheobronchial mucormycosis (TM) is a severe form of pulmonary mucormycosis in which the fungal infection is entirely or predominantly confined to the tracheobronchial tree. Previous studies described the primary bronchus as the most frequently involved branch, noting that Mucor has a predilection for upper lobes in patients with diabetes mellitus.4,5
The typical presentation of TM ranges from hoarseness and dysphonia to the presence of frank hemoptysis.6 Radiographic findings are nonspecific, with previous studies reporting that only 23% of TM patients have findings of tracheobronchial lesions.5 Thus, bronchoscopy is the ideal procedure to make a certain diagnosis. During direct visualization of the lesion, it can mimic a malignant tumor and is classically described as a lesion with gray-white mucoid material, surrounded by mucosal edema and necrosis, that obstructs the airway, as in our case.7 Definite diagnosis is achieved with biopsy of the lesion and subsequent histopathological examination, which reveals a tissue invasion by aseptate broad right-angled branching hyphae.6,7
The three mainstays of treatment are amphotericin B, surgical resection of the involved area of the lung, and control of the underlying disease.8 Oral isavuconazole or posaconazole are used either as step-down therapy in patients who responded well to amphotericin B or as salvage therapy in patients who cannot tolerate or do not respond to amphotericin B.8–10 In our case, we switched the patient to oral isavuconazole after she responded well to amphotericin B.
Wedge resection, lobectomy, and pneumonectomy have been described as independent protective prognostic factors in patients with TM.5 Furthermore, the combination of surgery and antimicrobial therapy showed an increased survival rate compared with surgery alone,11 particularly in patients with disease confined to one lung.8,12 Our cardiothoracic surgery team recommended against surgery due to the patient’s improvement on antifungal therapy.
The prognosis of patients with TM is poor and the mortality can vary based on the underlying condition of the patient. Patients with diabetes mellitus showed less mortality than patients with malignancy or hematological stem cell transplantation.13 The most common reason for death is fungal sepsis, followed by acute respiratory failure and hypovolemic shock due to massive hemoptysis. Due to the angioinvasive characteristic of the Mucor, massive hemoptysis is a frequent complication and has been described as a predictor of mortality in addition to dyspnea.5
In conclusion, pulmonary mucormycosis can rarely present as a right upper lobe consolidation with a bronchoscopy showing an erythematous mass mimicking a bronchial malignancy. Biopsy and histopathologic examination are key to confirm the diagnosis. This case emphasizes the need for a high degree of suspicion for pulmonary mucormycosis in cases of patients with diabetes ketoacidosis and upper lobe lung consolidation. This case also showed that antifungal therapy without surgery can be effective with favorable outcomes.
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