Diagnostic Puzzlers: A patient with progressive dyspnea and right heart failure
A 64-year-old woman with a history of uncorrected ventricular septal defect was hospitalized with progressive dyspnea and right heart failure. The patient had recently emigrated to the United States, where she received the diagnosis of ventricular septal defect with significant pulmonary arterial hypertension (Eisenmenger syndrome).
A 64-year-old woman with a history of uncorrected ventricular septal defect was hospitalized with progressive dyspnea and right heart failure. The patient had recently emigrated to the United States, where she received the diagnosis of ventricular septal defect with significant pulmonary arterial hypertension (Eisenmenger syndrome).
As part of her workup, a CT scan of the chest was obtained (Figure). Which of the following is suggested by her CT scan?
Pneumothorax
Solitary lung cyst
Chronic obstructive pulmonary disease
Congenital lobar emphysema
What do you suspect? How would you proceed?
A patient with progressive dyspnea and right heart failure: The CT scan revealed evidence of hyperaeration and hyperlucency in the right middle and upper lobes, suggestive of congenital lobar emphysema.
Discussion
Congenital lobar emphysema is characterized by progressive overdistention and air trapping in the affected lobe, concomitant compression of the remaining lung tissue, and displacement of the mediastinum by herniation of the emphysematous lobe across the anterior mediastinum into the opposite side of the chest.1 It is thought to be the result of a check-valve mechanism at the bronchial level that allows more air to enter the involved area on inspiration than to leave on expiration, causing progressive hyperinflation of the lung.2 Normally, the distribution of lobar involvement is left upper lobe, 45%; right middle lobe, 30%; right upper lobe, 20%; and lower lobes, 5%.3
Several mechanisms have been proposed to explain the pathogenesis of this condition. It is generally believed that congenital lobar emphysema is caused by an extrinsic or intrinsic bronchial obstruction or by an alveolar abnormality.4,5 Postulated causes of this obstruction include bronchial cartilage deficiency, dysplasia, inflammatory exudates, inspissated mucus, mucosal fold or web, bronchial stenosis, and extrinsic vascular or mass compression.6
Congenital lobar emphysema is mainly diagnosed in early infancy. In children, dyspnea, tachypnea, wheezing, cough, and cyanosis are among the common presenting signs and symptoms. Fifty percent of patients are symptomatic during the first year of life. There is a male-to-female predominance of 3:2.1 In rare instances, congenital lobar emphysema is discovered as an incidental finding in an asymptomatic adult.7,8
Many congenital abnormalities have been associated with congenital lobar emphysema. These include cardiovascular anomalies, such as patent ductus arteriosus, ventricular septal defect, and tetralogy of Fallot; diaphragmatic hernia; aplastic kidney; cleft palate; and pyloric stenosis.9
The diagnosis is established by clinical, radiologic and, if necessary, histologic findings. On a plain chest radiograph, congenital lobar emphysema appears as a translucency on the affected side, often with mediastinal displacement and compressed ipsilateral lobes. CT of the chest can help confirm the diagnosis. CT sometimes also allows delineation of the abnormal focal bronchial obstruction.
Nuclear scintigraphy shows decreased ventilation and matching decreased perfusion and delayed tracer washout in the emphysematous lobe. Bronchoscopy may be required to exclude a focal obstructive lesion.
Rarely, congenital lobar emphysema may be confused with tension pneumothorax or solitary lung cyst. Pulmonary vessels extend to the periphery of the hyperexpanded lobe, and there is no visualization of a pleural line, in contrast to tension pneumothorax. Decubitus and radiographic cross-table lateral views help distinguish congenital lobar emphysema from tension pneumothorax.
The definitive treatment for congenital lobar emphysema is surgical resection of the involved lobe; the prognosis is excellent.10 However, an increasing number of reports indicate that many patients can be treated conservatively with observation only.11 As a result, most pediatric pulmonologists now try conservative supportive treatment before resorting to surgery. Surgical intervention can be reserved for patients who do not improve with conservative treatment and for newborn infants with severe respiratory embarrassment.
There is a small group of patients in whom the malformation goes unrecognized in childhood. In these patients, a late complication or the coincidental discovery of a radiographic anomaly can lead to the diagnosis, as was the case with our patient, whose progressive dyspnea resulted from right heart failure. No treatment is needed if the adult is asymptomatic, but complications, such as pneumothorax or respiratory failure, require appropriate intervention.
Outcome in this case
The patient declined treatment with intravenous epoprostenol. She was sent home with the recommendation that she receive follow-up treatment in the pulmonary clinic, but she was lost to follow-up.
Case and photographs courtesy of Nick Patel, MD, Sophy Dedopoulos, ANP, Rakesh Shah, MD, and Arunabh Talwar, MD, of North Shore University Hospital, Manhasset, New York.
References:
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