Take-home point: When you are worried for ILD, always rule out infection first, and look for an underlying cause! When BAL is negative x48h, then you can consider empiric steroids. Steroids are really only useful for acute idiopathic ILD (COP and AEP) and for some ILDs from known causes (see “approach to ILD” below)!
An approach to ILD (thanks Lekshmi! Who also referenced our dean, Talmadge, for this framework!)
Break it down into FOUR main categories: known cause, idiopathic, granulomatous, and weird stuff (that only a pulmonologist needs to know J). Under idiopathic, further break it down into acute, chronic, and smoking-related.
And a few more pearls on ILD
- ALWAYS r/o infection!
- Try to find an underlying cause
- Bronchial biopsy can be very useful if it can be obtained!
- Alphabet soup: What about UIP (usual interstitial pneumonia)? Great question! This is a pattern – that is characteristic of end-stage IPF.
- Steroids are useful in acute idiopathic ILD and some forms of ILDs from known causes (eg connective tissue diseases). NOT useful in other forms. However, for critically ill patients in the ICU with respiratory failure from ILD flare, oftentimes our pulmonary experts will still recommend it
Lastly, some PEARLS on pulmonary NET
- Often associated with endobronchial tumors (which are associated with obstruction)
- Not all pulmonary NET are carcinoid! It is a big umbrella category and types of pulmonary NET include: pulmonary carcinoid, large cell neuroendocrine carcinoma of the lungs, and small cell lung carcinoma
- Our classic carcinoid syndrome (diarrhea, flushing; less frequently heart failure and bronchoconstriction) is from secretion of serotonin and kallikrein. Seen in 5% of carcinoid tumors when tumors escape hepatic degradation
- Think about paraneoplastic syndromes. As HH brought up, ectopic ACTH-secretion which can lead to glucocorticoid release can lead to an immunosuppressed state leading to atypical/opportunistic infections, which could broaden our differential. Thanks for clarifying this teaching pearl, Rafael!!
- Interestingly, pulmonary NET can shrink rapidly with radiation!