Allergic Bronchopulmonary Aspergillosis

Pathology and Pathogenesis

The hallmark of allergic bronchopulmonary aspergillosis (ABPA) is Òallergic mucinÓ which is composed of abundant eosinophilic mucin, mixed with eosinophils, eosinophil cytoplasmic debris, occasional CharcotÐLeyden crystals, as well as calcium oxalate crystals (Fig. 10.5). There are rare fungal hyphae in the mucin. Various combinations of asthmatic changes, bronchocentric granulomatosis, and eosinophilic pneumonia are commonly seen [19].

Symptoms and Signs

Clinically, the patients with ABPA present with chronic asthma, recurrent pulmonary inÞltrates, and bronchiectasis. Most complain of low-grade fever, wheezing, bronchial hyperreactivity, hemoptysis, or productive cough. Expectoration of brownish mucus plugs is seen in 31Ð69 % of patients [19]. Patients may be minimally symptomatic or asymptomatic.

CT Findings

CT Þndings of ABPA consist primarily of mucoid impaction and bronchiectasis involving predominantly the segmental and subsegmental bronchi of the upper lobes, along with centrilobular small nodules or branching linear structures [20] (Figs. 10.4 and 10.5). Bronchiectasis with mucoid impaction generates a gloved Þnger sign. In approximately 30 % of patients, the impacted mucus is highly opaque or demonstrates frank calciÞcation at CT [21] (Fig. 10.5).

CT–Pathology Comparisons

Airway colonization by Aspergillus causes persistent inßammation and Þbrosis, leading to segmental and subsegmental bronchiectasis and mucoid impaction [22]. High-attenuation mucus plugging is related to the presence of calcium salts [23]. Centrilobular small nodules on CT reßect the presence of dilated bronchioles Þlled with mucus or necrotic debris.

Patient Prognosis

Institution of glucocorticoids to control the immunologic activity and close monitoring for detection of relapses are the two important aspects of the management of ABPA. Because of frequent relapses (up to 45 %) with the lower doses of glucocorticoids, a higher dose and prolonged duration of

corticosteroid therapy are necessary. Antifungal therapy with itraconazole can be given with corticosteroid therapy in the relapsed patients.

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