We report three cases of pulmonary cystic disease in HIV positive individuals with multiple risk factors for the development of emphysema.
Although emphysema and bronchiectasis are defined by histopathological exam of lung biopsies, a diagnosis can be inferred based on chest X-ray, pulmonary function tests, and high resolution computed tomography (HRCT). In the absence of HRCT, as was the case in our centre, the exact diagnosis might be difficult to establish. Emphysema is only consistently diagnosed on chest X-ray when the disease is severe, diagnosed in about half the instances when the disease is of moderate severity and almost consistently missed in mild cases . Moreover, bullae reflect only locally severe disease and are not necessarily indicative of widespread emphysema. Bullae on conventional chest X-ray present as radiolucent areas larger than one centimeter in diameter surrounded by arcuate hairline shadows. In bronchiectasis, findings may be nonspecific and include focal pneumonitis, scattered irregular opacities, linear or plate-like atelectasis, or specifically dilated and thickened airways that appear as ring-like shadows or tram lines .
Several potential risk factors, such as intravenous drug use, repeated pulmonary infections, malnutrition and HIV infection itself have been described, but no rigorous case control studies have been published.
Intravenous injection of a number of oral medications has been associated with the development of talcosis and subsequently emphysema and bulla formation. Intravenous illicit drug use, methylphenidate in particular, has been linked to the development of a specific pattern of lower-lobe emphysema, resembling panacinar emphysema due to α1-protease inhibitor deficiency .
Recurrent infections, especially Pneumocystis jiroveci, have been associated with emphysematous changes and bronchiectasis in patients with HIV infection . Conversely, while tuberculosis is one of the most prevalent opportunistic infections in people living with HIV in resource poor settings, the association with emphysema and bronchiectasis has not been studied widely in this population .
Emphysema may also be a direct effect of the HIV virus. Reported by Diaz et al, four HIV infected patients without history of pneumonia, other pulmonary opportunistic infections or other known causes of emphysema, showed a markedly abnormal pulmonary function with air-trapping, hyperinflation, decreased diffusing capacity and emphysema-like bullous changes on HRCT . In one autopsy study of AIDS patients, infection of macrophages by the HIV virus resulted in the upregulation of matrix metalloproteases in neighboring uninfected macrophages and was strongly associated with loss of alveolar wall .
Lymphoid interstitial pneumonitis (LIP) has been suggested as an etiologic factor for bronchiectasis and bullae in HIV positive patients. Two patients with transbronchial biopsy evidence of LIP but no antecedent histories of infection have been reported to have CT-proven bronchiectasis . One case report described extensive bullae in the course of LIP .
Malnutrition and weight loss, common complications of HIV infection in resource poor settings, may affect human lung structure and function, as reported in starvation . While some authors argue that some of these changes may be reversible, the chronic catabolic state in HIV infection and insufficient calorie intake in sub Saharan Africa may lead to irreversible lung damage and chronic pulmonary disease . Furthermore, malnutrition increases the risk of infections in general .
Treatment options for emphysema and bronchiectasis are focused on symptom control, treatment of disease exacerbation and attempts to limit the rate of disease progression. In the absence of lung function tests, the assessment of clinical improvement following medical intervention will be limited and rely solely on patient history. Medical interventions include smoking cessation, bronchodilators, oxygen supplementation, and management of exacerbations with antibiotics . HIV positive patients should also be offered cotrimoxazole prophylaxis, isoniazid preventive therapy, and could benefit from vaccination against Haemophilus influenzae and Streptococcus pneumonia . Given the direct cytotoxic effect of HIV infection, inhibition of HIV replication at the lung compartment through ART may further modulate the disease . It remains however, unclear if ART should be considered in all HIV infected patients with proven emphysema or bronchiectasis, independent of CD4 count and clinical staging.
The commonest indication for surgical bullectomy is severe dyspnea in the setting of a large bulla occupying at least 30 percent of the hemi thorax. Although, lung volume reduction surgery improves survival compared to conservative therapy, it should be reserved for patients with upper-lobe-predominant emphysema in well-equipped and experienced treatment centers .