Asthma Patients, Take Note: When a "Common" Cough Lingers, Beware of Fungal Allergies in the Lungs
Introduction
For many asthma patients, coughing and wheezing are commonplace. But if conventional treatment is ineffective, symptoms recur, and even "unusual" signs such as weight loss, fever, and night sweats appear, it may not be a simple asthma attack. A cunning "mimic" may be hidden behind this – Allergic Bronchopulmonary Aspergillosis (ABPA). Recently, a case report published in the Annals of Internal Medicine and Surgery revealed the diagnostic challenges of this disease and reminded us to be vigilant about this rare but treatable lung disease.
Background: What is ABPA?
Our living environment is full of various microorganisms, one of which is a very common fungus called "Aspergillus," which is widely found in soil, air, and decaying organic matter. For most people, inhaling a small amount of Aspergillus spores does not cause any problems. However, for some people who suffer from chronic respiratory diseases such as asthma or cystic fibrosis, their immune system may overreact to Aspergillus that "colonizes" the airways, thereby triggering a severe allergic inflammation, which is ABPA.
Simply put, ABPA is not a direct fungal infection of lung tissue, but an "allergic attack" by the body against the fungus. This "civil war" can lead to airway inflammation and mucus blockage, and if not diagnosed and treated in time, it can eventually lead to bronchiectasis – a serious consequence of permanent widening and damage to the airways. It is estimated that about 2.5% of adult asthma patients worldwide may suffer from ABPA, but due to its symptoms being similar to common asthma attacks, pneumonia, and even tuberculosis, it is often missed or misdiagnosed.
Key Findings: A "Textbook" Case of Tortuous Diagnosis
The protagonist of this report is a 48-year-old male patient. He suffered from asthma since childhood, but his condition has been poorly controlled for the past five years, with recurrent lower respiratory tract infections. This time, he was admitted to the hospital due to coughing yellow sputum, chest pain after coughing, shortness of breath after activity, and systemic symptoms such as fever, night sweats, and a weight loss of about 10 kg in one and a half months. These symptoms made him and his doctors highly vigilant.
Initially, chest CT scans revealed multiple high-density shadows, cavities, and bronchial wall thickening in his lungs, and even mediastinal lymphadenopathy, which once led to suspicion of active pulmonary tuberculosis. However, after three sputum smears for tuberculosis bacteria were all negative, this possibility was ruled out. Subsequent bacterial cultures found other bacteria, but targeted antibiotic treatment was still not ideal.
The breakthrough in diagnosis came from a series of more in-depth examinations. The doctor's second CT scan found more suggestive imaging features: bronchiectasis and "ground-glass" opacities in both lower lung fields. More critically, blood tests showed that the patient's "eosinophil" count (a type of white blood cell related to allergic reactions) was as high as 11.5%, and total IgE levels (immunoglobulin E, a key antibody in allergic reactions) were also significantly elevated to 515.3 IU/ml. Finally, a positive skin prick test for Aspergillus confirmed the suspicion of an allergic reaction to Aspergillus.
Combining all clues – a history of underlying asthma, typical imaging findings, elevated eosinophil and IgE levels, and evidence of Aspergillus allergy – the doctors finally diagnosed him with ABPA.
Diagnosis and Treatment Methods (Brief)
This case clearly demonstrates the diagnostic approach for ABPA. It is not based on a single test, but a comprehensive judgment process of multidisciplinary evidence:
- Clinical Basis: Patients must have a history of asthma or cystic fibrosis.
- Immunological Evidence: Total IgE levels in the blood are usually significantly elevated (generally considered more specific if above 1000 IU/mL, but 515 IU/mL in this case is suggestive), and specific IgE levels against Aspergillus will also be elevated.
- Imaging Features: High-resolution CT is the preferred imaging examination, with typical manifestations including "central bronchiectasis" (airways thickening like fingers from the center of the lung outwards) and "mucus plugging" (thick mucus blocking the airways, forming the so-called "finger-in-glove sign").
After diagnosis, the treatment goal is to control allergic inflammation and clear fungi from the airways. The main treatment options include:
- Oral corticosteroids: These are cornerstone drugs for suppressing strong allergic reactions and controlling acute symptoms.
- Antifungal drugs: Such as itraconazole, which, although it cannot completely eradicate Aspergillus, can effectively reduce the number of fungi in the airways, thereby reducing immune system stimulation and playing a "steroid-sparing" role, reducing the side effects of long-term steroid use.
In recent years, with a deeper understanding of the pathogenesis of ABPA, some biologics targeting allergic pathways (such as omalizumab, mepolizumab) have also begun to be used in the treatment of refractory ABPA patients and have shown good prospects for reducing recurrence and improving lung function.
Limitations and Application Prospects
It should be clear that this is only a case report, and its conclusions cannot be directly generalized to all patients. However, it is highly educational, vividly demonstrating ABPA's "camouflage" ability and the complexity of diagnosis. In this case, the patient was once suspected of having pulmonary tuberculosis, which is one of the common misdiagnoses of ABPA worldwide.
This case and related review studies collectively emphasize the importance of "early diagnosis and early treatment." Each acute exacerbation of ABPA can cause irreversible damage to the lungs. If intervention can be performed in the early stages of the disease, inflammation can be effectively controlled, and permanent complications such as bronchiectasis can be prevented or delayed, thereby significantly improving patients' long-term prognosis and quality of life.
Summary
ABPA is an easily overlooked "complication" of asthma. This case reminds asthma patients and clinicians: when asthma symptoms become difficult to control, or when atypical symptoms such as coughing, sputum production (especially brownish-black mucous sputum), fever, and weight loss appear, one should broaden their thinking and consider the possibility of ABPA. Through timely immunological and imaging examinations, clear diagnosis, and correct hormone and antifungal treatment, permanent damage to lung function can be effectively avoided, allowing patients to regain smooth breathing.
