Differential Dx includes hiatal hernia
The differential diagnosis for achalasia includes hiatal hernia, right middle lobe pneumonia, empyema, and lung abscess. Most patients with hiatal hernias are asymptomatic, and the diagnosis is made incidentally on chest x-ray as a retrocardiac air-fluid level or on upper gastrointestinal studies. Right middle lobe pneumonia would appear on chest x-ray as a well-demarcated opacity within the confines of that lobe, but would not have an air-fluid level. Empyema and lung abscess are complications of pneumonia, and patients present with persistent fever, cough, dyspnea, and malaise. With an empyema, chest x-ray reveals a pleural effusion. A lung abscess is an intrapulmonary cavitary lesion with an air-fluid level, most commonly due to aspiration pneumonia.
This patient’s chest x-ray showed a mass outside the lung tissue and pleural space that had an air-fluid level, was within the mediastinum, and displaced the trachea anteriorly, all suggestive of a dilated esophagus filled with undigested food unable to pass the LES.
Esophageal manometry clinches the diagnosis
Esophageal manometry is the gold standard for diagnosis. In achalasia, manometry shows poor peristalsis of the esophageal body and a constricted LES that does not relax sufficiently with swallowing.3 Manometry cannot, however, reliably distinguish primary achalasia from pseudoachalasia.
Barium swallow studies and endoscopy can assist in the diagnosis and help rule out pseudoachalasia. Timed barium studies can show a lack of peristalsis, an air-fluid level at the top of a barium column retained within the dilated esophagus, and the narrowing of the distal esophagus into the pathognomonic “bird’s beak” of primary achalasia.4 Endoscopy can visualize a mass beyond the LES, but cannot adequately assess esophageal peristalsis or LES relaxation.1