Allergic bronchopulmonary aspergillosis: high-attenuation mucous plugging

A 27-year-old male patient presented at the emergency room with cough and dyspnoea with three weeks of evolution, associated with fever and chest pain for the last two days. On auscultation, there were diminished breath sounds over the right chest, associated with crackles. The patient had a history of asthma.

The chest radiograph showed an opacity with lobulated contours in the right mid zone (para-hilar) (Fig. 1). Therefore, a computed tomography (CT) was performed, revealing large cystic and varicose bronchiectasis, almost all distributed centrally in the right upper lobe, that were occluded by mucoid impaction, resulting in bronchocele with the typical “finger in glove”-sign (Figs. 2 and 3). These mucous plugs have high density, greater than the soft tissue attenuation (Fig. 4). There are bronchial wall thickening and air-fluid levels inside the ectatic airways. The pulmonary parenchyma exhibits ground-glass opacities, associated with centrilobular nodules (Fig. 5). These imaging findings are typical of allergic bronchopulmonary aspergillosis, which were corroborated with clinical and laboratory data (elevated total serum IgE and specific IgE and IgG to Aspergillus fumigatus). In addition, the patient underwent bronchoscopy, that showed purulent secretions emerging from the right upper lobar bronchus, with isolation of Aspergillus fumigatus.

Allergic bronchopulmonary aspergillosis (ABPA) is a pulmonary disorder characterised by a hypersensitivity reaction to Aspergillus spp, involving type I (IgE-mediated) and type III (IgG-mediated) immunologic responses. [1,2,3] This entity is most commonly encountered in adults before the age of 40 years, with longstanding asthma, that is the most important contributing factor (occurs in 0.25-11% of asthmatic patients). It is seen occasionally associated with cystic fibrosis and other underlying bronchiectatic diseases.[2] Patients generally experience symptoms of recurrent asthma exacerbations (wheezing, cough and dyspnoea). Occasionally, chest pain, fever, expectoration of dark mucous plug and haemoptysis may be associated. [3,4] The established major criteria for the diagnosis of ABPA include history of asthma, immediate skin reactivity to Aspergillus, elevated total serum IgE (>1000 ng/ml), elevated IgE or IgG to Aspergillus and central bronchiectasias. [2,4] The disease progression may be divided into five phases: acute presentation; resolution with clearing of pulmonary abnormalities and decline in serum IgE; recurrence; development of dependence on corticosteroids; and rarely leading to pulmonary fibrosis. [3] The diagnosis is frequently missed on chest radiographs, since it is normal in almost half of the cases. CT is preferable for its higher sensitivity and specificity. [1,2] The radiological findings consist primarily of central bronchiectasis (cystic or varicose) and mucoid impaction of underlying bronchiectatic airway, forming large bronchoceles, typically with involvement of the upper lobes. On imaging, it corresponds to tubular branching opacities extending from the hilum with the appearance of “finger in glove”, that may be associated with air-fluid levels in dilated bronchi. Pulmonary collapse may be seen as a consequence of endobronchial mucoid impaction. [1,2,5] Hyperattenuating mucus on CT scans has been reported as a diagnostic criterion for ABPA, corresponding an attenuation superior to 70 Hounsfield Unit (denser than the para-spinal muscles). It is currently attributed to the fungal metabolism by calcium salts and metals (iron and manganese) and desiccated mucus. [1,2,4,6] The presence of hyperdense mucous plugging impaction has been shown as a 100% specific criterion of ABPA and thus may be considered pathognomonic. [2,6,7] Other CT findings in acute exacerbation of ABPA include bronchial wall-thickening, centrilobular nodules (as tree-in-bud pattern), consolidation and mosaic pattern with air trapping. [1,2,5,6] Treatment of ABPA aims to control inflammation and prevent further injury to lungs, based on the combination of oral corticosteroids and anti-fungal medications. The prognosis is excellent in stages I to III and rarely progress clinically. [7,8] Written informed patient consent for publication has been obtained.