INTRODUCTION:The Zygomycetes are a group of fungi found commonly in soil and decaying organic matter. Family members that infect humans include Mucor, Rhizopus, Absidia and Cunninghamella species. These spore forming saprophytes can infect humans by inhalation of aerosolized spores and is associated with a very high morbidity and mortality due to the fact that it causes vascular invasion, tissue necrosis and infarction. Rhizopus infections in immunocompromised patients are rare and usually cause diffuse pulmonary involvement. Primary tracheal rhizopus infection is very unusual and has only been rarely reported in the literature.
CASE PRESENTATION:A 23 year old man with diabetes and Philadelphia-negative acute lymphocytic leukemia (ALL), status post induction and consolidation chemotherapy with hyper-CVAD and Rituxan, presented to MD Anderson Cancer Center. Two years previously he had been diagnosed with and treated for a chest wall Aspergillosis Flavus infection and for an abdominal wall Nocardia Brasiliensis infection. The leukemia had recently progressed and salvage chemotherapy with liposomal vincristine and dexamethasone was started. During the current presentation, he described symptoms of vague right sided chest discomfort for one week, cough productive of a scant amount of brown sputum and progressive shortness of breath. He was admitted to the hospital for evaluation and treatment with empiric antibiotics. There was a subsequent rapid deterioration in his respiratory symptoms with an ‘underwhelming’ chest × ray for which we were consulted for evaluation. The patient was febrile, otherwise hemodynamically stable with pulse oximetry reading of 95% on room air. He was ‘severely’ tachypneic with loud inspiratory and expiratory breath sounds but without significant findings on his lung exam. On review of his laboratory results he was profoundly neutropenic and his chest x ray was essentially normal. With the suspicion that he may have an endobronchial pathology, we proceeded to a bronchoscopy upon which we found profound, diffuse mucosal sloughing with polyp like structures extending into the airway causing significant narrowing of the lumen. These changes extended from the proximal trachea upto the right distal bronchus intermedius. There was no involvement of the left tracheobronchial tree or remaining visible airways. Washings were taken of the involved airway and smears and cultures revealed fungal elements consistant with Rhizopus species. Patient was continued on liposomal amphotericin despite which patient developed severe hypoxic respiratory failure requiring mechanical ventilation. He expired after 2 days despite ongoing efforts. Autopsy showed microvascular emboli secondary fungal invasion.
DISCUSSIONS:Primary endobronchial rhizopus infection has rarely been reported. Such cases are associated with mucosal ulceration, vascular invasion leading to profound tissue necrosis and destruction of the normal bronchial architecture. Prognosis is poor with a mortality rate of higher than 50%. Of the 17 cases reported in the literature 82% were in diabetic patients. Our patient had a particularly rapid progression predisposed not only by diabetes but also by a diagnosis of leukemia, neutopenia and recent chemotherapy. He also had two previous, unrelated fungal infections treated with prolonged courses of antifungals that may have predisposed him to particularly aggressive strain of rhizopus. A high level of clinical suspicion is essential in making the diagnosis especially with negative radiographic studies as was the case in this situation. Rapid diagnosis may limit the extent of tissue necrosis hence allowing for prompt surgical intervention. Previous reports have demonstrated that without resection of the involved trachea followed by amphotericin B mortality has been 100%.
CONCLUSION:Primary endobronchial rhizopus infections are often fatal. To increase chances of cure, a high level of clinical suspicion, prompt diagnosis and initiation of effective antifungal therapy and surgical resection when deemed feasible must be instituted.
DISCLOSURE:Ruckshanda Majid, No Financial Disclosure Information; No Product/Research Disclosure Information