A 51-year-old man presents to the emergency department complaining of fever and a cough with yellow-green sputum for the past 3 days. He denies any hemoptysis, facial pain, rhinorrhea, or night sweats. The patient reported similar symptoms 2 months ago. Chest radiograph performed at the time was notable for a right middle lobe consolidation. He was diagnosed with lobar pneumonia and completed a 7-day course of antibiotics with complete resolution of his symptoms. He has no other significant medical history and does not take any medications. He has smoked 1 pack of cigarettes a day for 35 years and drinks 3 beers per week. He is sexually active with his wife. His temperature is 101.7°F (38.7°C), blood pressure is 127/85, pulse is 102/min, and respirations are 22/min. Physical exam is notable for decreased breath sounds on the right side without wheezing and increased dullness to percussion on the right side. A chest radiograph is ordered and reveals a consolidation in the right middle lobe. Which of the following is the most appropriate next step in management?
Interferon-gamma release assay
CT of the chest without contrast
Barium swallow
Serum immunoglobulin levels
CT of the chest without contrast
This patient's presentation with recurrent pneumonia in the same anatomical location is concerning for an anatomic abnormality. Given his history of heavy smoking, lung cancer should be ruled out with a chest CT with possible subsequent bronchoscopy for tissue biopsy.

Recurrent pneumonia can be classified either as those confined to 1 anatomical location of the lung or those involving different portions of the lung. If recurrent pneumonia is limited to a single region, the patient should be evaluated for an anatomic obstruction, such as a mass or mucous plug. Obstruction will hinder mucociliary clearance and allow for the proliferation of bacteria, leading to recurrent infections. The most concerning etiology of such an obstruction is a tumor causing external bronchial compression. Thus, patients should be screened with a chest CT to rule out lung cancer in these cases. If lesions are identified on CT, subsequent bronchoscopy or CT-guided biopsy may be warranted. Treatment may involve radiotherapy, chemoimmunotherapy, or surgery depending on the underlying malignancy. Other causes of recurrent pneumonia limited to an anatomical region include recurrent aspiration secondary to tracheoesophageal disorders or seizures.

Purysko et al. discuss the role of contrast enhancement in chest CTs. The authors find common indications for contrast-enhanced chest CTs include investigation for pulmonary embolism, pleural pathology, or hilar pathology. The authors recommend against the regular use of contrast enhancement in chest CTs outside of selected indications as they rarely provide additional diagnostic benefits while subjecting the patient to the risk of adverse effects with contrast agents.

Incorrect Answers:
Answer A: Barium swallow is often done to investigate anatomical abnormalities of the upper gastrointestinal tract such as tracheoesophageal fistula or Zenker diverticulum. These can increase the risk of aspiration and lead to recurrent pneumonia. In a patient with positive risk factors for cancer, chest CT to rule out malignancy would be the most appropriate next step.

Answer C: Human immunodeficiency virus (HIV) can cause secondary immunodeficiency, which can predispose patients to recurrent infections. These recurrent pneumonias would be expected to be in different regions of the lung and not anatomically confined.

Answer D: Interferon-gamma release assay can be used to diagnose tuberculosis (TB). Reactivation of TB will present clinically with fever, cough, hemoptysis, and night sweats. Chest radiography will commonly reveal an upper lobe infiltrate.

Answer E: Serum immunoglobulin levels would be an appropriate next step to diagnose primary immunodeficiencies such as common variable immunodeficiency or other antibody defects. This would present with multiple lung infections in different regions of the lung. Moreover, these patients would be expected to have other infections such as sinusitis, otitis, and gastrointestinal infections.

Bullet Summary:
Recurrent pneumonia in the same anatomical region should be worked up with a CT with subsequent bronchoscopy and biopsy to rule out malignancy.