To the Editors,
A 35-yr-old Caucasian female was admitted with a 2-week history of rapidly progressive dyspnoea on minimal exertion. She denied any associated cough, chest pain or systemic symptoms. She gave a background of a 5-yr history of dyspnoea on moderate exertion, with intermittent cough, but no diurnal variation. This had been previously attributed to asthma and she had been maintained on inhaled corticosteroids and short-acting β-agonists. She had no symptoms suggestive of any connective tissue disease. She had no family history of respiratory disease. She was a heavy smoker, having accrued a 10-pack-yr history of smoking, but denied any illicit drug use. She was unemployed. There was no history of exposure to hazardous dusts.
Physical examination revealed reduced air entry throughout all lung fields but worse on the right, with ipsilateral hyperresonance. A chest radiograph (fig. 1a⇓) showed a right pneumothorax with bilateral diffuse reticular infiltrates predominantly affecting the mid-zones. There were no previous radiographs for comparison. An intercostal drain was inserted and the lung re-expanded. She underwent a high-resolution computed tomography scan of the thorax (fig. 1b⇓ and c), which revealed the presence of large bilateral bullae in the upper zones, with infiltrates in a bronchovascular distribution. She subsequently underwent a video-assisted thoracoscopic biopsy of her middle lobe as well surgical pleurodesis. The histology confirmed the presence of noncaseating granulomas (fig. 2⇓). Fungal and mycobacterial stains were negative. A diagnosis of bullous sarcoidosis was made.
a) Anteroposterior chest radiograph on admission demonstrating a pneumothorax on the right, hyperinflated lung fields and faint infiltrates throughout the mid- and lower zones. b) Bullae in the upper zones on high-resolution computed tomography (HRCT). c) HRCT showing parenchymal infiltrates in a bronchovascular distribution.
Histology specimen of middle lobe demonstrating noncaseating granulomas.
Serum angiotensin-converting enzyme was elevated at 160 U·mL−1 and α1-antitrypsin level was within normal limits.
Her lung function tests at baseline showed a forced expiratory volume in 1 s (FEV1) of 1.18 L (3.26 L predicted) and forced vital capacity (FVC) of 2.24 L (3.75 L pred), with a FEV1/FVC ratio of 52%. Diffusing capacity of the lung for carbon monoxide (DL,CO) and carbon monoxide transfer factor were 33% and 58% pred, respectively. Her 6-min walk distance was 389 m with exertional desaturation from 98% to 86% and a pre-test Borg score of 3 and post-test Borg score of 6. She was commenced on oral prednisolone, initially at 30 mg·day−1 with gradual dose tapering over subsequent months to 10 mg·day−1. The patient noted symptomatic improvement after introduction of steroids, although no changes in her physiological parameters occurred over the subsequent 2 yrs of follow-up.
Sarcoidosis, a granulomatous disorder of unknown aetiology, characteristically involves multiple organs, with lung involvement being predominant. The diagnosis of sarcoidosis is based upon the association of compatible clinicoradiological findings, histological demonstration of noncaseating granulomas, and exclusion of other granulomatous disorders. The pulmonary manifestations of sarcoidosis are diverse, involving the intrathoracic lymph glands and pulmonary parenchyma, as well as the airways. Occasionally, sarcoidosis has been reported to have atypical thoracic manifestations. One such example is the bullous form of the disorder. The condition was first reported in 1949 by Zimmerman and Mann 1. A Medline has further revealed a total of 17 more case reports of bullous sarcoidosis search since then 1–10.
The age at diagnosis of bullous sarcoidosis varied from 21 to 64 yrs with a mean age of 37 yrs. Males were more frequently affected than females in a ratio of 2:1. In only half of the cases was the race specified 1, 3, 5, 7, 9, 10 and no ethnic differences in incidence was noted. Most patients had been noted to have bullous changes within 3–4 yrs of symptom development 2–4, 7. In four patients, the symptoms had been attributed to asthma or chronic obstructive pulmonary disease (COPD) 7, 9, 10. Smoking history was not specified in six of the 18 case reports. Of the remaining 12 patients, three were never-smokers 2, 4, 7, while two had smoking history of <10 pack-yrs 7. Seven patients had presented with single or recurrent pneumothoraces, affecting the right more frequently than the left 2, 4–6, 10.
Lung function showed an obstructive picture in 11 cases 1–3, 4, 7, restrictive in three cases 2, 5, 6 and preserved spirometry in one case 10. In all cases in which DL,CO was measured, significant impairment in the values were noted 4, 7, 10. Few of the reports specifically mentioned the site of predominance of the bullae, but were noted to involve the lower as well as the upper zones equally.
Systemic steroids were given to 10 patients, with variable outcomes 2, 4–7. Duration of follow-up was highly variable amongst the case reports. Five reported improvement or stability in symptoms, lung function and/or radiographic appearance 4, 6, 7. However, response to corticosteroid therapy was only transient in three further cases, with further deterioration in symptoms and lung function. Five patients underwent bullectomy, two of which were bilateral 2, 3, 5, 7, 10. Of these, four had improved while one patient 3 had enlarging contralateral bullae and respiratory failure. One patient underwent single lung transplant 7, owing to worsening lung function and was noted to remain stable on follow-up. Five of the cases were reported to die with respiratory failure and cor pulmonale, two of whom were aged <35 yrs 1–3, 8.
The precise mechanism underlying the formation of bullae remains unclear, and various mechanisms have been proposed 7, as follows. 1) Ball-valve obstruction, whereby endobronchial involvement by sarcoid lesions causes peripheral air trapping and alveolar distension and rupture. However, it is noteworthy that endobronchial involvement with sarcoidosis has not been universally found in cases where the bronchi were biopsied 10. 2) Formation of bullae by retraction and collapse of surrounding disease lung. 3) Presence of an inflammatory alveolitis, with release of many inflammatory mediators, resulting in tissue destruction.
Although considered to be rare, it is not inconceivable that bullous sarcoidosis may in fact be under-recognised for a variety of reasons. Patients frequently present with nonspecific symptoms, including intermittent wheeze and cough, and these are often attributed to other conditions, such as asthma and smoking-related COPD, especially when there is concurrent heavy smoking history. Bullous lung changes, especially in the upper zones in smokers, may often be attributed to smoking and alternative diagnosis may not be sought. Also, paucity of granulomatous changes 10 have been noted along the walls of bullae, which were resected and examined, hence highlighting the need for biopsy of relatively spared lung tissue as well when attempting histological diagnosis.
There is an increasing number of case reports of bullous sarcoidosis, suggesting that the condition may not be a rare entity as previously considered. It is interesting to note that a recent histopathological review of lung volume reduction surgery specimens revealed noncaseating granulomatous changes in nine out of 80 cases 11. Most of the patients retrospectively, however, did not have clinical characteristics attributable to sarcoidosis, although mediastinal adenopathy was noted in the vast majority of the patients. A prospective study of cases referred for bullectomy or lung volume reduction surgery would be useful.
From a clinical perspective, one should maintain a high index of suspicion in a young patient with or without significant smoking history, especially when other radiographic abnormalities or clinical features to suggest extrapulmonary sarcoidosis coexist. It is important to recognise that the vast majority of patients may present early in the course of their illness with bullous disease, with a probable poor response to corticosteroid therapy, and among them a subset who rapidly progress to respiratory failure and cor pulmonale. The need for consideration of bullectomy or lung transplantation should be actively sought, although the criteria for patient selection are unclear.
Statement of interest
None declared.
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