Allergic bronchopulmonary aspergillosis: a view from India.

It was with great interest that I read the article by Dr. Al-Amoudi1 and the comments by Dr. AlMobeireek.2 Both pulmonary tuberculosis (TB) and allergic bronchopulmonary aspergillosis (ABPA) can present with a similar clinical and radiological picture.3,4 Predominantly a disease of asthmatics, ABPA is characterized by repeated episodes of exacerbations interspersed with periods of remission culminating, if untreated, in fibrotic lung disease which can resemble the chronic fibrocavitary disease of pulmonary tuberculosis.5 When we evaluated 23 patients with ABPA to study the computerized tomography (CT) appearances, we found that 83% of these patients, prior to presentation, had received anti-tuberculous therapy for a long duration.6 The radiologic appearances in ABPA closely resemble those seen in TB. However, serial roentgenograms may reveal the transient nature of these pulmonary infiltrates, also known as 'fleeting shadows', a feature characteristic of ABPA.7 Although cavitation is not common in ABPA,6,8 aspergilloma formation in these cavities has been reported.4,9,10 This could also lead to diagnostic confusion, as aspergillomas are known to form in tuberculous cavities.11 Dr. Al-Mobeireek also described a patient with concomitant ABPA and TB,2 but in our recent analysis of 95 patients with ABPA12 we were unable to detect any patient with coexisting TB. However, we are in agreement with Dr. AlMobeireek that prophylactic therapy for tuberculosis should be considered when commencing systemic steroids in patients with ABPA.2 Dr. Al-Amoudi has quoted a 5-15% prevalence of ABPA from Western studies but a majority of the studies quoted are those of patients with cystic fibrosis,1 while Dr. AlMobeireek found a prevalence of 2.7% among their asthmatic subjects.13 A recent literature review on the epidemiology of ABPA states that the disease may be present in 0.2-0.8% of all asthmatic patients in the United States of America.14 We recently determined the sensitization to Aspergillus antigens in 105 patients with bronchial asthma.15 We found that 30 (28.5%) patients were sensitized to Aspergillus antigens while 8 (7.6%) fulfilled all the 8 major criteria for the diagnosis of ABPA. Although ABPA is a disease with a worldwide distribution,16 the variable prevalence rates probably reflect the lack of a single diagnostic criterion with a standardized test. Central bronchiectasis with normal tapering peripheral bronchi still remains a prerequisite for the diagnosis of ABPA.17,18 To add to the discussion, we would like to stress that allergic Aspergillus sinusitis (AAS),19 a more recently recognized form of Aspergillus-related hypersensitivity respiratory disorders, should also be looked for in patients with ABPA.20-22 In our analysis of 95 patients with ABPA, we were able to confirm the presence of concomitant AAS in 7 of the 9 patients who underwent the invasive procedure required for diagnosis.12 However, the frequency of AAS among our patients with ABPA could be higher since 13 others with radiologic evidence of sinusitis refused to undergo the surgical procedure. This review suggests that the co-occurrence of ABPA and AAS may not be as rare as it appears and it is imperative that the occurrence of AAS in ABPA and ABPA in AAS should be looked for.12,23 In conclusion, ABPA must be excluded in all asthmatic subjects with a positive skin prick test to Aspergillus antigens. Furthermore, the remarkable radiologic similarity to pulmonary tuberculosis has important clinical implications in high tuberculosis prevalent areas as patients with ABPA often receive antituberculous therapy for a long time while lung damage continues to progress relentlessly.7,24 Early diagnosis and appropriate therapy could alter the natural history of the disease and prevent the development of end-stage lung fibrosis.