Allergic Bronchopulmonary Aspergillosis Aided by Bronchoalveolar Lavage: A Case Report

Summary

This protocol outlines a stepwise diagnostic workflow for young, atypical patients with allergic bronchopulmonary aspergillosis (ABPA) unresponsive to antibacterial therapy. It includes bronchoscopy, analysis of bronchoalveolar lavage fluid (BALF), and targeted next-generation sequencing (tNGS) to detect Aspergillus fumigatus sequence reads, with informed consent and ethical approval.

Abstract

This protocol establishes a clear primary goal: to develop a structured, actionable diagnostic workflow that enables accurate differentiation of allergic bronchopulmonary aspergillosis (ABPA) from other chronic respiratory diseases with similar presentations in young patients with refractory respiratory symptoms. In this population, ABPA is frequently misdiagnosed due to non-classical clinical features, leading to avoidable delays in targeted therapy and persistent diagnostic uncertainty in routine clinical practice. The diagnostic workflow is designed as an integrated, multi-step approach incorporating comprehensive clinical assessment, high-resolution computed tomography (HRCT), bronchoscopy, and bronchoalveolar lavage fluid (BALF) analysis, including galactomannan assay, alongside targeted next-generation sequencing (tNGS) to detect Aspergillus fumigatus sequence reads. These components function as adjunctive tools within a holistic framework, guiding clinicians through the sequential evaluation of atypical ABPA cases. To demonstrate clinical applicability, the workflow was implemented in a 22-year-old male patient with a 10-year history of recurrent cough and sputum production, who had been initially misdiagnosed with infectious bronchiectasis and was unresponsive to antibacterial therapy. Application of the workflow enabled integration of serial HRCT findings, BALF testing, tNGS results for Aspergillus fumigatus sequence reads, and baseline serological data, ultimately leading to a definitive diagnosis of ABPA. This protocol highlights that a multimodal diagnostic strategy can enhance diagnostic confidence in young patients with refractory respiratory symptoms and elevated serum IgE levels, reducing diagnostic ambiguity and facilitating timely initiation of targeted anti-inflammatory and antifungal therapy to improve clinical outcomes.

Introduction

The primary goal of this case report is to illustrate a structured diagnostic workflow for identifying ABPA in young patients with atypical clinical presentations and a history of misdiagnosis.

ABPA is an allergic lung disease caused by Aspergillus spp., particularly Aspergillus fumigatus. Its clinical manifestations are complex and heterogeneous, primarily characterized by asthma-like episodes, recurrent infiltrative shadows on pulmonary imaging, and bronchiectasis. In 1952, British scholar Hinson first described this condition¹. As a progressive disease, ABPA presents with complex clinical features and intricate diagnostic criteria and is often misdiagnosed as bronchiectasis with infection or simple asthma^2,3. Diagnostic criteria for ABPA have been outlined in the International Society for Human and Animal Mycology (ISHAM) guidelines and the 2022 Chinese Expert Consensus^4,5. These include major features (elevated serum total IgE, Aspergillus-specific IgE positivity, and radiological abnormalities) and minor features (peripheral eosinophilia and Aspergillus-specific IgG positivity), all of which must be evaluated for diagnosis^4,5.

This case is noteworthy for addressing a critical gap in clinical practice: the diagnosis of ABPA in young patients with non-classical presentations. Unlike most reported cases involving middle-aged or elderly patients with documented asthma, this 22-year-old male patient had no prior asthma diagnosis, only mild respiratory symptoms at admission, and a long-standing misdiagnosis of “infectious bronchiectasis.” The case highlights a pivotal clinical decision point: when conventional antibacterial therapy fails and serum IgE is markedly elevated (>10 times the upper normal limit), diagnostic escalation with minimally invasive sampling and advanced molecular testing becomes imperative. This scenario is common yet underreported, making the structured workflow described here highly instructional for clinicians.

Existing ABPA diagnostic pathways prioritize serum-based testing and radiology; however, these approaches have limitations. Serum galactomannan is false-negative in 30%–50% of non-invasive ABPA cases⁶, and HRCT findings overlap with those of bronchiectasis, pneumonia, and chronic obstructive pulmonary disease⁷. BALF analysis enables the detection of local fungal biomarkers, while tNGS allows the sensitive identification of Aspergillus fumigatus sequence reads. However, these tools remain underutilized due to concerns regarding invasiveness, cost, and lack of standardized integration into diagnostic workflows. This case contextualizes their role within a stepwise framework aligned with emerging multimodal diagnostic approaches^4,5.

This diagnostic approach is applicable to patients with chronic or recurrent respiratory symptoms lasting at least 3 months, unresponsive to antibacterial therapy, with HRCT evidence of bronchiectasis or consolidation, and elevated serum IgE (>500 IU/mL) or eosinophilia (>500 cells/µL). Caution is warranted in patients with contraindications to bronchoscopy or low pretest probability.

By integrating clinical, radiological, and laboratory data, this case provides an actionable workflow for ABPA diagnosis in young, atypical patients and emphasizes the complementary role of BALF biomarkers and tNGS (55 Aspergillus fumigatus sequence reads; detection threshold: ≥10 reads)^8,9,10.

Case presentation:
During clinical evaluation, differential diagnoses—including infectious bronchiectasis, chronic pneumonia, and chronic obstructive pulmonary disease (COPD) exacerbation—were comprehensively considered and excluded.

A 22-year-old male was admitted with a 10-year history of recurrent cough and expectoration, which had worsened over 2 days. There was no family history of tuberculosis or asthma. The patient had a 2-year smoking history (20 cigarettes per day). The patient reported slight chest tightness and cough-related pain. Oxygen saturation was 93% while the patient was receiving oxygen inhalation at 5 L/min. Auscultation revealed slight wet rales in the upper right lung without wheezing. Breath sounds were diminished, and the patient exhibited expiratory dyspnea.

Preliminary laboratory tests showed a total IgE level of 1400 IU/mL (upper normal limit: 100.0 IU/mL). Serum Aspergillus immunological testing combined with fungal D-glucan detection showed 1-3-β-D-glucan at 25.1 pg/mL and Aspergillus galactomannan at 0.016 S/CO. HRCT confirmed upper-lobe inflammation with partial consolidation and bronchiectasis in both lungs (Figure 1).

The patient was initially diagnosed with pulmonary infection and treated with piperacillin–tazobactam and ambroxol. After one week, HRCT showed persistent inflammation with partial consolidation in both upper lobes, progression in the left upper lobe, bronchial mucus impaction in the right upper lobe, and bilateral upper lobe bronchiectasis (Figure 2).

Following bronchoscopy, purulent mucus plugs were observed, and brown mucopurulent sputum plugs were aspirated. BALF cytology showed a galactomannan level of 3.344 S/CO. tNGS detected 55 Aspergillus fumigatus sequence reads, while routine microbial culture was negative.

Diagnosis, Assessment, and Plan:
The patient was diagnosed with ABPA and received methylprednisolone (40 mg/day) combined with voriconazole (200 mg every 12 h). After 10 days, symptoms improved, and therapy was transitioned to oral treatment.

Follow-up HRCT demonstrated reduced pulmonary inflammation, resolution of mucus plugs, and persistent bronchiectasis in the right lung (Figure 3). The patient was discharged on oral corticosteroids and fluconazole (200 mg every 12 h).

At follow-up more than 6 months after diagnosis, the patient’s condition remained improved, with further resolution of pulmonary lesions compared with baseline.

Protocol

This study was approved by the Ethics Committee of Minhang Hospital, Fudan University (Approval No.: 2025-018-01K). Written informed consent was obtained from the patient prior to all clinical procedures, in compliance with the ethical principles of the Declaration of Helsinki. All patient data were anonymized, and no identifiable personal information was disclosed in this report. The reagents and equipment used are listed in the Table of Materials.

1. Pre-treatment evaluation and empirical therapy initiation

1. A detailed clinical history and symptom assessment were conducted. The following baseline laboratory examinations were performed: complete blood count, arterial blood gas analysis, respiratory pathogen panel (including SARS-CoV-2 and EBV), Aspergillus serology, and a fungal (1,3)-β-D-glucan assay.
2. Chest computed tomography (CT) was performed to evaluate pulmonary inflammatory lesions and structural abnormalities based on abnormal peripheral blood test results suggestive of infection.
3. A bronchial dilation test was performed to screen for underlying asthma in the presence of cough, expectoration, and wheezing. Sputum culture with drug sensitivity testing and acid-fast bacilli staining were performed to identify pathogenic microorganisms and exclude pulmonary tuberculosis.
4. Empirical treatment was initiated based on integrated biochemical and chest CT findings suggestive of pulmonary infection, including oxygen therapy, intravenous piperacillin–tazobactam for anti-infective therapy, and ambroxol for expectoration and mucolysis.

2. Antibacterial therapy efficacy evaluation and diagnostic escalation

1. A follow-up chest CT scan was obtained to assess treatment efficacy and disease progression in the absence of clinical improvement following antibacterial therapy.
2. Bronchoscopy was performed for mucus plug removal in cases with radiological evidence of disease progression and mucus plug formation. BALF was collected and submitted for cytological analysis, routine microbial culture, and Aspergillus fumigatus-specific antibody testing.
3. Targeted anti-allergic and antifungal therapy was initiated and adjusted based on positive Aspergillus fumigatus-specific antibody test results, including intravenous methylprednisolone (40 mg once daily) and intravenous voriconazole (200 mg every 12 h).

3. Targeted therapy response assessment and regimen adjustment

1. A third chest CT scan and a comprehensive panel of biochemical tests were performed to assess the therapeutic response to targeted anti-allergic and antifungal therapy.
2. For patients demonstrating significant clinical and radiological improvement, therapy was transitioned to an oral maintenance regimen consisting of oral voriconazole (200 mg every 12 h for 4 months) and oral prednisone (35 mg once daily, tapered to 15 mg once daily after 2 weeks, then further reduced to 5 mg once daily for an additional 2 weeks before gradual discontinuation).

4. Long-term maintenance therapy monitoring and biomarker follow-up

1. Repeat chest CT scans were performed to evaluate the resolution of pulmonary inflammatory lesions and structural changes.
2. Serum total IgE levels and peripheral blood eosinophil counts were reassessed to monitor improvement in ABPA-related laboratory biomarkers.

Results

The patient’s clinical course demonstrated significant improvement following targeted therapy for ABPA, with systematic changes observed in diagnostic biomarkers, radiological findings, and clinical symptoms.

The patient was initiated on methylprednisolone (40 mg/day) and voriconazole (200 mg every 12 h). Within 10 days, marked improvement in cough, expectoration, and dyspnea was observed. Follow-up HRCT scans (Figure 3) demonstrated resolution of mucus plugs, red...

Discussion

In China, bronchiectasis is a common chronic respiratory disease with a relatively high incidence. Among individuals aged 40 years or older, post-infectious bronchiectasis is more prevalent⁷. Although allergic bronchopulmonary aspergillosis (ABPA) is not uncommon in clinical practice, misdiagnosis and missed diagnosis remain frequent due to non-specific symptom descriptions, inconsistent diagnostic criteria, and other contributing factors⁸. Early and accurate diagnosis, alo...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Aspergillus-specific IgE Assay Kit	Thermo Fisher Scientific, USA	ELISA Aspergillus sIgE Kit	Enzyme-linked immunosorbent assay for Aspergillus-specific IgE detection; cutoff: >0.35 kUA/L; patient result: 2.8 kUA/L
Aspergillus Galactomannan Assay Kit	Bio-Rad Laboratories, USA	Platelia Aspergillus Ag EIA	Enzyme immunoassay (EIA) for Aspergillus galactomannan detection; serum result: 0.016 ODI, BALF result: 3.344 ODI; cutoff: >0.5 ODI
Aspergillus fumigatus-specific IgG Assay Kit	Thermo Fisher Scientific, USA	ELISA Aspergillus fumigatus IgG Kit	Enzyme-linked immunosorbent assay for Aspergillus fumigatus-specific IgG detection; cutoff: >1.0 AU/mL; patient result: 1.6 AU/mL
Acid-fast bacilli taining kit	Solarbio, China	AS-1010	Diagnostic Reagents/Tests
Ambroxol	Boehringer Ingelheim International GmbH, China	ABX-30	Therapeutic Drugs
Automated biochemical analyzer	Roche Diagnostics, Switzerland	cobas 8000	Serum IgE/eosinophil testing
BAL collection tubing kit	Medtronic plc, China	49445	Sample Collection Materials
BALF collection container	Corning, USA	352070	Sample Collection Materials
Bronchoscope	Olympus Corporation, Japan	BF-1TQ290	Lower respiratory tract sampling
Chest CT	Siemens, GER	Somatom Definition Force	High-resolution computed tomography (HRCT) scanner used for pulmonary
Drug sensitivity testing reagents	BD, USA	BD BBL Sensi-Disc	Diagnostic Reagents/Tests
Electronic medical record system	Cerner Corporation, USA	Millennium	Patient data management
Fungal (1,3)-β-D-Glucan Assay Kit	Associates of Cape Cod, China	Fungitell	Quantitative chromogenic assay for fungal (1,3)-β-D-glucan detection; normal range: <20 pg/mL; patient result: 25.1 pg/mL
Flexible Bronchoscope	Olympus, Japan	BF-1T260	Bronchoscope with 2.8 mm working channel; used for airway inspection and BALF collection from right upper lobe posterior segment
Fluconazole	Pfizer Inc, USA	FLC-200	Therapeutic Drugs
Hematology Analyzer	Sysmex	XN-9000	Automated hematology analyzer used for peripheral blood eosinophil count; patient pre-treatment result: 850 cells/μL
HRCT image analysis software	Siemens Healthineers, Germany	syngo.via	Pulmonary lesion quantification
Methylprednisolone	Pfizer Inc, USA	MP-40	Therapeutic Drugs
Microbial culture incubator	Thermo Fisher Scientific, USA	3110	BALF microbial culture
Piperacillin–tazobactam	Pfizer Inc, USA	TZP-4.5	Therapeutic Drugs
Prednisone	Pfizer Inc, USA	PDN-5	Therapeutic Drugs
Respiratory pathogen panel (SARS-CoV-2, EBV)	BGI Genomics, China	2019-nCoV/EBV-001	Diagnostic Reagents/Tests
Serum Total IgE Assay Kit	Beckman Coulter, China	Immage 800 IgE Kit	Quantitative ELISA kit for serum total IgE measurement; normal upper limit: 100 IU/mL; used to detect elevated IgE (1400 IU/mL) in the patient
Sputum culture media	Thermo Fisher Scientific,USA	TSA-100	Diagnostic Reagents/Tests
Sterile saline for lavage	Baxter, China	0.9% NaCl-500mL	Sample Collection Materials
Targeted Next-Generation Sequencing (tNGS) Platform	BGI Genomics, China	MGISEQ-2000	Metagenomic sequencing platform for BALF DNA analysis; detection threshold: ≥10 sequence reads; identified 55 Aspergillus fumigatus sequences
tNGS Library Preparation Kit	Illumina, USA	MGIEasy DNA Library Prep Kit	Library preparation kit for microbial DNA sequencing; used for BALF sample processing prior to tNGS
tNGS data analysis software	Illumina, USA	BaseSpace	Sequence read alignment/identification
tNGS sequencing platform	Illumina, USA	NextSeq 550	tNGS sequencing platform
Voriconazole	Pfizer Inc, USA	VRC-200	Therapeutic Drugs