- Practice reading CXRs
- Differential of cystic lung disease
A 41 yo homeless M with no significant PMH who presented with acute onset chest pain and SOB 2 weeks ago. The pain and shortness of breath were intense initially but subsequently improved and he attempted to “wait it out.” However, over the past day, he’s had increasing shortness of breath and palpitations. He denies any fevers, chills, night sweats, URI symptoms and has had a chronic productive cough that he attributes to smoking. He noticed a change in his cough ~ 1 month ago and has been able to produce thick yellow sputum over this time. He additionally reports a 30 lb weight loss over the past 1-2 months.
He has no known PMH and takes no medications. He has a 20 pack year smoking history and is a heavy THC user. He is currently homeless and has been in jail multiple times in the past year. On exam, he is afebrile 36.8C, HR 126, RR 32, BP 159/91. Initially found to be 88% on RA. He was laced on 100% NRB with saturations down in the high 80s.
Before you examine the patient, what does his response to 100% NRB tell you about the cause of hypoxemia?
Lack of improvement with 100% FiO2 oxygen suggests the presence of a large shunt.
While you could get an ABG to further work-up his hypoxia, based on his response to 100% NRB alone, you know he will have an elevated A-a gradient secondary to shunting.
BMP – Na 133, K 4.5, Cl 97, CO2 31, BUN 36, Cr 1.3
CBC – WBC 16k, Hb 14.9/hct 46, Plts 342
VBG: 7.31/59/42/34 (not ABG for reasons above)
What would you do now?
Even though he’s not currently hypotensive, he has evidence of tension physiology on CXR and needs a urgent chest tube placement! If he showed signs of hypotension, he would need emergent needle decompression.
A CT showed (click to show CT interpretation):
What disease processes cause cysts in the lung?
- Normal incidental finding
- COPD and other emphysematous diseases (e.g., alpha 1 antitrypsin deficiency)
- Infectious causes
- Pneumocystis jiroveci pneumonia, coccidioidomycosis
- Atypical and tuberculous mycobacteria
- Bacterial pneumonia can be associated with pneumatoceles (commonly Staph)
- Paragonimiasis, echinococcosis
- Connective tissue disease – Ehlers-Danlos, Marfan syndrome
- Interstitial lung disease
- Desquamative interstitial pneumonia
- Lymphangioleiomyomatosis (LAM)
- Lymphocytic interstitial pneumonia (LIP)
- Idiopathic pulmonary fibrosis (IPF)
- Langerhan’s cell histiocytosis – associated with multiorgan involvement and endocrinopathies
- Metastatic disease especially with squamous cancer of head and neck
- Birt-Hogg-Dube syndrome – autosomal dominant syndrome characterized by cutaneous fibrofolliculomas, lung cysts, spontaneous PTX, and renal cancer.
The number and location of cysts as well as any associated findings (ground glass opacities, nodules, fibrosis) can point to a diagnosis. History can also help differentiate between some of these diagnoses (e.g., LAM almost exclusively occurs in women of childbearing age).
What is your differential for his lung findings?
- Re-expansion pulmonary edema in underlying cystic/bullous lung disease
- Community acquired bacterial pneumonia (in underlying cystic lung disease)
Our highest suspicion was for re-expansion pulmonary edema in underlying bullous lung disease likely 2/2 to COPD/emphysema. We suspected he’s likely had the PTX for ~ 2 weeks (onset of symptoms) putting him at higher risk of reexpansion pulmonary edema. Given productive cough and leukocytosis, there was also concern for underlying CAP and he was started empirically on ceftriaxone/azithromycin.
The prolonged history of cough and prominent weight loss raised the question for TB (given history of homelessness and incarceration), underlying immunodeficiency, and malignancy. His CT chest did not reveal any high suspicions and cystic metastatic disease is relatively rare. His HIV was negative so PJP was felt to be unlikely.
Less likely, but we also considered DIP, which occurs in patients 40-60, more commonly in men and almost exclusively in smokers. He otherwise denied any family history of connective tissue diseases or personal history of joint hypermobility.
FINAL DIAGNOSIS AND OUTCOME:
He had persistent symptoms and pneumothorax after pigtail placement and ultimately underwent apical bleb resection and mechanical pleurodesis.
- Raoof, S et al. “Cystic Lung Diseases: Algorithmic Approach.” 2016. CHEST. 150(4):945-965.