Early diagnosis of invasive pulmonary mycoses in immunocompromised patients is a major determinant of effective treatment. However, making a reliable diagnosis is challenging and often requires transbronchial or even surgical lung biopsy. We provide evidence that endobronchial ultrasound-guided transbronchial needle aspiration may be an attractive, less invasive diagnostic method. Endobronchial ultrasound-guided transbronchial needle aspiration was not only a diagnostic clue in the presented kidney transplant recipient with invasive pulmonary mycosis but was useful in assessment of treatment efficacy.
Key words : Fungal lung diseases, Invasive pulmonary aspergillosis, Immunocompromised host, Transplant recipient
Invasive pulmonary mycoses (IPM) are severe fungal infections seen mainly in severely immunocompromised patients. High-risk populations include hematopoietic stem cell and solid-organ transplant recipients, patients with prolonged neutropenia, and patients receiving prolonged systemic corticosteroid treatment.1,2 Molds, particularly Aspergillus species, are responsible for the vast majority of invasive pulmonary fungal infections.1 Fatality rate in patients with invasive pulmonary aspergillosis is as high as 30% to 60%, and delay in diagnosis is associated with significant increase in mortality. However, early diagnosis of IPM is challenging. This is well reflected by the 3 levels of IPM probability proposed by a panel of experts.3
Bronchoscopy and bronchoalveolar lavage play pivotal roles in the diagnosis of pulmonary infections in immunocompromised patients. However, as transbronchial forceps lung biopsy can only be considered in selected patients, direct histopathologic proof of lung invasion by fungal hyphae is only rarely available. In recent years, there has been growing interest in the use endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) as a diagnostic tool in pulmonary diseases, including lung and mediastinal lymph node infections.4-6
We present a kidney transplant recipient who developed invasive pulmonary aspergillosis and in whom EBUS-TBNA was the only diagnostic clue for pulmonary fungal infection.
A 46-year-old male patient was admitted to the Department of Transplantation Medicine and Nephrology because of high fever (up to 40°C), chills, severe dry cough, and general weakness for 4 weeks. He had undergone kidney transplantation due to chronic renal failure secondary to polycystic kidney disease 3 months before admission. Since then, he had been receiving immunosuppressive treatment with prednisone, tacrolimus, and mycophenolate mofetil, as well as co-trimoxazole and valganciclovir. His medical history also included right native nephrectomy due to polycystic kidney disease 3 years ago, arterial hypertension, and multiple hepatic cysts.
Physical examination on admission revealed a febrile patient (38°C) in relatively good general condition, with normal heart, breath, and bowel sounds and no abdominal tenderness, particularly in the left lower abdominal quadrant (the site of the transplanted kidney). Basic blood laboratory studies showed an elevated C-reactive protein level (44.6 mg/dL), decreased hemoglobin level (106.0 g/L), normal white blood cell count (8.1 × 109 /L) with neutrophil predominance (80%), and elevated creatinine level (22.0 mg/L). Urinalysis revealed no abnormalities. Chest radiograph demonstrated slight pulmonary hilar enlargement with no clear evidence or parenchymal consolidation or pleural effusion. Abdominal ultrasonography showed an enlarged native left kidney with multiple cysts filled with echogenic fluid and multiple cystic liver lesions. Because bacterial infection of the native cystic kidney was suspected, treatment with antibiotics was initiated (ceftriaxone and clarithromycin, followed by amoxicillin with clavulanic acid, clindamycin, imipenem); however, there was no clinical improvement. All blood and urine cultures were negative. Cytomegalovirus and Epstein-Barr virus infection were excluded with polymerase chain reaction method. Blood tests for Aspergillus, Candida, and Cryptococcus antigens were negative. Chest computed tomography revealed right hilar lymphadenopathy, a mass in the apical segment of the right lower lobe (RB6), and pulmonary nodules in the left lung (Figure 1). A tentative diagnosis of posttransplant lymphoproliferative disease was established.
The patient was referred to our Department of Internal Medicine, Pneumonology, and Allergology for further diagnosis. Bronchoscopy showed edematous bronchial mucosa in the area of the division of the right main stem bronchus into the upper lobe and intermediate bronchi. Large heterogeneous nodular masses behind the posterior wall of the right main bronchus and just below the upper lobe carina were identified with EBUS. Bronchoalveolar lavage of the right apical segments and EBUS-TBNA of the right hilar lymph nodes (Figure 2A) were performed.
Flow cytometry analysis of lymph node aspirates showed significant predominance of neutrophils (83%), with only 4% lymphocytes and 3% monocytes. Direct microscopy and polymerase chain reaction for Mycobacterium tuberculosis complex (GeneXpert MTB-RIF, Cepheid, Sunnyvale, USA) of bronchoalveolar lavage fluid and the material from EBUS-TBNA did not demonstrate mycobacteria. Bronchoalveolar lavage fluid cultures were positive for Escherichia coli (105 CFU/mL) and Candida albicans (104 CFU/mL). The immunoenzymatic test for Aspergillus galactomannan in bronchoalveolar lavage fluid was negative (index = 0.491, cut-off value < 0.5). However, cytologic examination of EBUS-TBNA revealed numerous hyphae (consistent with Aspergillus species infection), neutrophils, and foci of necrosis (Figure 2B). Given the signs and symptoms, the results of chest imaging, and the cytopathologic appearance of the EBUS-TBNA samples, together with the high probability of invasive Aspergillus infection (due to immunosuppression), invasive pulmonary aspergillosis was diagnosed, and treatment with voriconazole (200 mg twice daily, orally) was started. Antimicrobial treatment with imipenem was continued as culture-directed therapy for Escherichia coli infection. Gradual clinical and radiologic improvements (Figure 3A and 3B) were observed. However, follow-up EBUS-TBNA after 12 weeks still revealed fungal hyphae in biopsy samples. Treatment with voriconazole was continued. Computed tomography scan after 6 months of treatment showed further resolution of pulmonary and mediastinal lesions (Figure 3C and 3D), and no hyphae were detected in subsequent EBUS-TBNA samples. Antifungal treatment was continued for 8 months.
The presented case shows that EBUS-TBNA is a useful tool in the diagnosis of pulmonary complications in immunocompromised patients. Because EBUS-TBNA is less invasive than transbronchial lung biopsy, it might be considered the sampling method of choice in immunocompromised patients with pulmonary or mediastinal lesions adjacent to the large airways.
Pulmonary infiltrates are a common complication in patients with severely impaired immune function and are often associated with a fatal outcome. Bronchoscopy has been shown to have a higher efficacy than noninvasive diagnostic methods such as serologic tests, blood antigen detection and blood or nasopharyngeal wash cultures, sputum analyses, and tracheobronchial aspirate cultures.7 However, most of the studies to date have focused on the usefulness of bronchoalveolar lavage, bronchial washing, and protected specimen brush sampling.7,8 Only few reports have addressed the value of EBUS-TBNA.5
Invasive pulmonary aspergillosis is a rare but important clinical problem in renal transplant recipients. The incidence of invasive pulmonary aspergillosis in this group is lower than in stem cell or other solid-organ recipients (0.7%-4%), but it is related with a very high mortality rate (75%-80%).9 The diagnostic approach in this group of patients does not differ from that used in other immuno-compromised patients, with bronchoscopy playing the key role. However, procedure-related complications associated with transbronchial lung biopsy or open lung biopsy limit their use.10,11 Other diagnostic methods such as cultures of various samples from the airways or the assessment of galactomannan, an Aspergillus cell wall component, in bronchoalveolar lavage fluid and serum are also useful. However, some of these methods show specific limitations when applied in solid-organ transplant recipients.12-14
In our patient, serum galactomannan was measured twice, and both results were below the cut-off value (< 0.5). Galactomannan was also not detected in bronchoalveolar lavage fluid; however, the index was close to the cut-off value (0.491). Bronchoalveolar lavage fluid cultures did not demonstrate fungal growth. Unfortunately, EBUS-TBNA samples were not sent for mycologic examination. Polymerase chain reaction was not performed. Thus, our diagnosis of IPM was based solely on the cytopathologic examination of lymph node samples obtained in EBUS-TBNA. The lack of confirmation of Aspergillus infection in cultures of the respiratory samples may be considered as a shortcoming, as there are fungi species that have similar microscopic appearance (45-degree branching, septate, hyphae; eg, Fusarium, Scedosporium, Pseudallescheria, Penicillium species, Zygomycetes).3,14 However, Aspergillus species are the most common molds causing invasive infections and the second most frequent cause of invasive fungal infection in solid-organ transplant recipients, following Candida species.15 Our diagnosis of mold invasive pulmonary disease may be further supported by the significant improvement during treatment with voriconazole. Paradoxically, the facts that IPM could be diagnosed by EBUS-TBNA irrespective to negative fungal cultures and the absence of Aspergillus antigens further support the value of this bronchoscopic procedure in the diagnosis of pulmonary mycoses in immunocompromised patients. There are only few papers on the use of TBNA in the diagnosis of invasive pulmonary fungal infections to date.4,5
To conclude, EBUS-TBNA can be used as a diagnostic tool in immunocompromised patients suspected to have invasive pulmonary fungal disease. It may offer a definite diagnosis even in culture-negative cases with the absence of fungal antigens in blood and bronchoalveolar lavage fluid.
Volume : 16
Issue : 3
Pages : 333 - 336
DOI : 10.6002/ect.2015.0366
From the 1Department of Internal Medicine, Pneumonology and
Allergology; the 2Department of Transplantation Medicine and
Nephrology, Transplantation Institute; and the 3Department of
Pathology, Medical University of Warsaw, Poland
Acknowledgements: The authors declare that they have no sources of funding for this study, and they have no conflicts of interest to disclose.
Corresponding author: Rafal Krenke, Department of Internal Medicine, Pneumonology and Allergology, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
Phone: +48 22 599 2562
Figure 1. Axial Contrast-Enhanced Thorax Computed Tomography Scan on Admission
Figure 2. Axial Contrast-Enhanced Thorax Computed Tomography Scan on Admission
Figure 3. Axial Contrast-Enhanced Thorax Computed Tomography Scans After 3 and 6 Months of Treatment