ABPA sans asthma: an entity to remember

Background

Allergic bronchopulmonary aspergillosis (ABPA) is a common allergic respiratory mycosis in patients with asthma and cystic fibrosis. It has a global prevalence of 2.5% (approximately 5 million in 193 million) of asthmatics.1 ABPA is a severe allergic respiratory mycosis caused by Aspergillus fumigatus. The research interest and diagnostic criteria for the disease have evolved over the past two decades. A rare subset of ABPA is the one without asthma, known as ABPA sans asthma, which was first reported in 1981; however, to date, less than 50 cases have been reported worldwide.2 Given their non-specific presentation, they may be wrongly diagnosed as tuberculosis or lung malignancy without a high index of clinical suspicion. Herein, we report a rare case of ABPA sans asthma, which we successfully diagnosed and managed.

Case presentation

A male patient in his 20s presented with a 1-year history of occasional dry cough and small-volume haemoptysis. He had no history of fever, loss of appetite, weight loss or other constitutional symptoms. He was treated with multiple courses of antibiotics and was prescribed empirical antituberculosis therapy based on chest radiograph. He came for second opinion to our institute. He was a non-smoker and gave no significant medical or surgical history or contact with open tuberculosis cases. On physical examination, his vitals were stable. A respiratory system examination revealed a reduced intensity of breath sounds in the right mammary region and tubular bronchial breath sounds and crackles but no wheeze. Other system examinations were normal. A right middle lobe consolidation was suspected, with possible differential diagnoses of infectious aetiologies, such as tuberculosis. Tuberculosis was considered the first differential diagnosis due to its high prevalence in Asia, followed by vasculitis and bronchial carcinoid tumour.

Investigations

Blood investigations revealed peripheral eosinophilia (AEC-1192) with normal liver and renal function tests. Sputum bacterial culture was negative; sputum smear for acid fast bacilli as well as catridge based nucleic acid amplification testing (CBNAAT) for Mycobacterium tuberculosis were negative. Blood cultures were sterile, and acute phase reactants were mildly elevated. Vasculitis work-up, urine routine and paranasal sinus imaging were normal. The chest X-ray showed right paracardiac opacity (figure 1A). Hence, a high-resolution CT of the thorax was done, which showed right middle lobe bronchiectasis with high-attenuation mucus plugging (figure 1B–D), very typical of ABPA.

Given the above features, the possibility of ABPA was considered when the serum total IgE was 9132 IU/mL, Aspergillus-specific IgE was 0.7 kU/L and skin prick testing for A. fumigatus (figure 2) was positive. A detailed work-up was negative for asthma, including a history of asthma or atopy, spirometry with bronchodilator reversibility testing and methacholine challenge test. A bronchoscopy with bronchoalveolar lavage and biopsy revealed fragments of clumps of degenerated basophilic necrotic debris admixed with eosinophils, suggestive of allergic-impacted mucin-like material, and the fungal culture grew A. fumigatus. A diagnosis of ABPA sans asthma was considered at this point.

Differential diagnosis

For the initial presentation of the non-smoker young man with cough and small-volume haemoptysis for a year, the differential diagnoses considered were chronic infections like tuberculosis and also vasculitis and slow-growing malignancies such as carcinoid. Imaging features with peripheral eosinophilia pointed towards ABPA; the rest of the criteria were fulfilled except for asthma, which was ruled out clinically and based on pulmonary function and bronchoprovocation tests. Other differential diagnoses, like vasculitis and carcinoid, were ruled out by lack of other supportive features of vasculitis like negative anti neutrophil cytoplasmic antibodies (ANCAs), normal sinus X-rays and urine routine examination. In view of focal consolidation of right middle lobe, an endobronchial lesion such as carcinoid or foreign body was also thought of, which was ruled out by flexible bronchoscopy. Hence, the diagnosis of ABPA sans asthma was confirmed, based on clinical, radiological and bronchoscopy guided lavage and biopsy features.

Treatment

Unlike ABPA, there are no guidelines, consensus statements or randomised controlled trials for managing ABPA sans asthma. Hence, an expert opinion was sought, and the patient was started on itraconazole 200 mg two times per day for 16 weeks, along with airway clearance techniques and pulmonary rehabilitation. Post-treatment clinical review and imaging revealed significant improvement (figure 3).

Outcome and follow-up

The patient had symptomatic improvement, with no further episodes of haemoptysis for 1 year.