Original case provided by Lauren Brown, MD.
Edits, graphics and teaching points by Yilin Zhang, MD.
- Evaluation of a patient with nonresolving pulmonary infiltrate
A 40 yo M presents with a 5 month history of nonproductive cough. He reports chest congestion and the feeling of a “rattling” in his chest. He reports a possible aspiration episode at the start of his symptoms. He denies any fevers, chills, night sweats or weight loss. He has no other PMH and takes no medications. He was never a smoker, works in a lab working with microbiology plates. He grew up in the Pacific Northwest and has traveled to ID. He denies any international travel.
On exam, his vital signs are normal, SaO2 99% on RA. Lungs are clear to auscultation.
His CXR shows:
He was treated with a 5 day course of azithromycin for presumed pneumonia. When should you repeat imaging to ensure resolution of this consolidation?
Patients should have subjective clinical improvement within 2-3 days of appropriate antibiotic therapy. Imaging findings of pneumonia can persist for several weeks after treatment (timeline of radiographic resolution of pneumonia). A CXR should be repeated in 4-8 weeks to ensure resolution of the consolidation1 (The British Thoracic Society guideline recommends 6 weeks2). Of note, the rate of resolution depends on the type of infection and patient comorbidities1,3 (factors affecting radiographic resolution). Incomplete resolution suggests an alternative diagnosis (e.g. malignancy, interstitial pneumonias, inadequate antibiotic coverage, atypical or nonbacterial infections) and warrant further imaging and evaluation.
He had minimal change in his symptoms after antibiotics. Repeat CXR was obtained 4 weeks later:
Interval improvement but persistent consolidation of the RUL.
He subsequently underwent a chest CT:
What is your differential for this CT finding?
- Fungal infection (including Aspergillus)
- Atypical bacterial infections (mycobacteria, Nocardia, Actinomyces)
- Benign airway lesions resulting in incomplete mucus clearance (e.g. adenoma, cylindroma)
- Pulmonary infarct
What would be your next step in evaluation?
He should undergo further work-up for atypical infectious causes with sputum cultures for bacteria, fungi and AFB. These can be done with expectorated sputum or with bronchoscopy. Given that malignancy is on the differential, bronchoscopy allows for tissue biopsy as well.
FINAL DIAGNOSIS AND OUTCOME:
He underwent bronchoscopy which revealed normal airways, negative bacterial, fungal cultures, Aspergillus PCR, Nocardia PCR and AFB cultures. Biopsy results did show at least adenocarcinoma in situ with possible invasive features.
He was referred to Oncology for further staging and subsequently underwent RUL lobectomy with resection of a well differentiated, 4 x 3.5 x 3.5 cm adenocarcinoma with negative margins and negative lymph node.
TAKE HOME POINTS:
- Patients without radiographic resolution of “pneumonia” 4-8 weeks after treatment should undergo CT imaging and consideration of bronchoscopy to further evaluate for noninfectious or atypical infectious causes.
- Low, DE, Mazzulli, T & Marrie, T. Progressive and nonresolving pneumonia. Current Opinion in Pulmonary Medicine. 2005; 11: 247-252.
- Lim, WS, et al. British Thoracic Society guidelines for the management of community acquired pneumonia in adults: update 2009. Thorax. 2009; 64(Suppl III): iii1-iii55.
- Johnson, JL. Slowly resolving and nonresolving pneumonia: Questions to ask when response is delayed. Postgraduate Medicine. 2000. 108(6): 115-122.