Episode 81: Eosinophilic Lung Disease

Hello and welcome to another episode of MedPod FMC. I am Major Hari Krishnan, hosting on behalf of Brigadier J. Muthur Krishnan, Sena Madal, V. S. Seva Madal. Through this podcast, we have put forth numerous topics of relevance for undergraduates, medical officers, residents and young specialists. Today, we bring in front of you another such topic that often gets overlooked. The topic is "Yershnophilic lung disease". To break this down ever so confusing list of differentials, we have our expert for the day, surgeon, sub-lefinant Srinath Vasudev, a pulmonologist of national repute. Welcome to the podcast Srinath and thank you for being a part of this initiative. Thank you, Dr. Hari Krishnan. Thanks for the invite. It's great to be here and I'm really excited to talk about one of my favorite tropics, eosinophilic lung diseases. So then let's start with the basics. What exactly is eosinophilic lung disease and how do you define it? To define it, eosinophilic lung disease is actually a spectrum of disorders where there is presence and a pathogenic role of eosinophils. So it is a lung disease characterized by eosinophilic inflammation. So this eosinophilic inflammation can be in the parenchyma or the airway or it can be restricted to the lung vasculature. So all this comes under the spectrum of eosinophilic lung diseases. Great. So for our listeners, it's almost a no-brainer. I would say it's a group of lung disorders with increased eosinophil which can be at various locations. So now that makes sense. So, Ashinath, when should a clinician suspect eosinophilic lung disease in a patient? That's a good question. For a physician, we should always suspect eosinophilic lung diseases when there is a combination of three things. Because a patient will be symptomatic. So there will be respiratory symptoms like cough, dyspnea, chest tightness, wheezing. Some may have some extra pulmonary symptoms, systemic symptoms like fever, weight loss, night sweats. So with this symptoms, patient will have peripheral eosinophilia. There is more than 500 cells per microlitre eosinophils. And along with that, there is an abnormal chest tingling which can be in the form of consolidation, airspace opacities or reticular opacities. So whenever a patient has respiratory symptoms with lung opacities in chest radiography and peripheral eosinophilia, we should always suspect eosinophilic lung diseases. Great. And now from what I could make out, eosinophilic lung disease is an umbrella term which is used for a wide spectrum of lung disorders with eosinophilia. So in that case, how do we categorize it for a more definitive clinical diagnosis? Okay, so eosinophilic lung diseases, the hallmark is eosinophilic lung inflammation. So how I would like to classify this eosinophilic lung disease is based on which part is predominantly, so where the inflammation is predominantly there. So if the inflammation is predominantly in the vasculature, so it is EGPA, there can be predominant inflammation of the airway like ABPA, Dress, Hess. Or there can be a predominant eosinophilic inflammation of the parangamma, which is eosinophilic pneumonia. So which eosinophilic pneumonia can again be classified as idiopathic, like idiopathic acute eosinophilic pneumonia, idiopathic chronic eosinophilic pneumonia. Or it can be eosinophilic pneumonia can be secondary to conditions like infections, mostly parasitic or fungal infection, or it can be due to drugs or radiation therapy. Great, that was very succinctly classified, Srinath. And now moving forward, once we suspect eosinophilic lung disease, how should we approach our cases to get to these diagnosis that you just mentioned? Sure, always suspect when the patient has some respiratory symptoms with chest radiography findings and eosinophilia. The approach to diagnosis starts with a good history and clinical examination. In history, we should look for what are the respiratory symptoms? A good respiratory history should be there. And there are some features in history which can point towards diagnosis, like coughing out of thick mucus, which predominantly shows towards ABPA, a long indelent cause of symptoms, more towards chronic eosinophilic diseases. And along with respiratory symptoms, try to elicit extra pulmonary symptoms like any neuromuscular involvement, any cardiovascular or any skin lesion. So these all take diagnosis, most towards eGPA address like this. Along with this, we should always take a history of exposures, like cigarette exposure, or exposure to a large volume of pollutants, which can lead to conditions like eosinophilic pneumonia. And travel history is the patient where is the patient resident of any endemic region and also a good drug history. So once we get a good history, what I do to approach these diseases, once we have a good history, if there is predominantly extra pulmonary symptoms, like predominantly, along with respiratory symptoms, are predominant neuromuscular skin lesions, predominant cardiovascular symptoms, which takes your diagnosis more towards eGPA address like condition. If it is a lung limited condition, then we have what we have, parenchymal disease, which is eosinophilic pneumonia or the ABPA. Next comes the role of chest radiography, X-ray is not a specific, there is no specific findings in X-ray, but HRCT is very much important. So if it is an airway-centric eosinophilic lung disease like ABPA, the predominant radiographic finding will be bronchectasis. And along with the central bilateral bronchectasis, there will be features of small airway environment, that is nodules in brain but patterns, along with other specific findings like ham, which is very specific for ABPA, high attenuating mucus. And if there is a predominant, if it is a parenchymal disease like eosinophilic pneumonia, so the radiography will show features of parenchyme environment, like GGOs, which shows allular inflammation or consolidation, which is allular filling up with some X-rays. So when there is consolidation GGOs, it is pointing towards pneumonia, eosinophilic pneumonia. So in chronic eosinophilic pneumonia, this consolidation and GGOs will be peripheral, subdural and more towards the upper zone. Lower lobe involvement is very much rare in chronic eosinophilic pneumonia. While in acute eosinophilic pneumonia, the same consolidation and GGOs will have a diffuse distribution. Entire lobe will be involved, it looks like ARDS picture, along with interlobular septal thickening and some conditions, there is pleural effusion. So once we have this radiological picture, then we have other blood investigation. So if it is eGPA, it will look for vasculitis workup, if it is ABPA, it will look for blood tests like serum tautal IgE, aspergillus specific IgE and IgE. And if there is eosinophilic pneumonia, first my approach will be to look for any treatable causes, any secondary cause of eosinophilic pneumonia. Like I will have a bowel look for any various infectious causes. I will do a parasitic serology stool test and if there is no known cause, then it takes your diagnosis most towards idiopathic acute eosinophilic pneumonia and idiopathic chronic eosinophilic pneumonia. And there is certainly a role of bowel in this condition. So a bowel cytology like eosinophilic count more than one person is significant. So if a bowel eosinophilic count is more than 40%, it takes your diagnosis more towards chronic eosinophilic pneumonia. If it is more than 25% but less than 40%, it is more towards acute eosinophilic pneumonia. So this is how I generally approach eosinophilic pneumonia. That's a very well structured and thought of approach Srinath. But to the list that you added, I have always had this doubt about the role of lung biopsy in the diagnosis of eosinophilic lung disorders. Is it actually required at all? Mostly not because if we have a structured approach with good clinical examination, radiological findings. So if you have a structured approach, there is no need of lung biopsy. We can stop at most with bowel. So bowel, only thing we have to do is the bowel should be processed very immediately. It should be a good bowel. It should be processed ideally within hour. So if we have that, there is no much need of lung biopsy. It is only restricted to fewer cases where there is a doubt regarding diagnosis. Great, great. Now we have diagnosed the case using whatever the test that you have just mentioned. Now that we know this is the disease, eosinophilic, the spectrum from the spectrum. This is the particular disease that we are dealing with. How do you approach treating such a case, Srinath? The treatment depends, first thing is for secondary causes. So if the eosinophilic lung disease is due to secondary conditions like infections, we should treat the infections. It can be parasites or antifungals. So it is due to any drugs, stop the offending drug. So if it is not a secondary eosinophilic lung disease, if it is a idiopathic eosinophilic pneumonia, the connoisseur of treatment will be steroids. Eosinophilic pneumonias respond exceptionally good to steroids. So there is a saying that if it does not respond to steroids, it is not eosinophilic pneumonia. So that will respond to steroids. ABPA, the connoisseur is also steroid therapy. There can be added on antifungals. And EGPA, it is also steroid therapy. The only difference between the treatment of ABPA, EGPA and eosinophilic pneumonias is the dose of steroids. Like acute eosinophilic pneumonias and chronic eosinophilic pneumonias, those will be much higher in case of IOPA and much, much higher in case of EGPA, where there can be a also need of other immunosuppressants like cyclophosphamide. Along with the steroids, there is an emerging role of biological agents, especially the anti-Alpha therapy, Mipoli and Ventralizumab. And there are also role of Mipoli and Ventralizumab therapy, especially in ABPA. So from my understanding, I always thought of ABPA as an immune response rather than more of a fungal involvement. Because I am asking this question because you happen to mention the role of antifungals in treating. Can you just elaborate for the benefit of our listeners, the role of antifungals in ABPA? Absolutely. Actually ABPA, as you said, is an immune response to fungals. The role is mainly of steroids. Antifungals is reserved for those patients who does not respond to steroids or when the steroid is tapered off, they have a relapse. So any patients who have a relapse of disease when we taper off steroids, they are good candidates for antifungal therapy. Great. Another thing which I wanted to know are about the long-term complications we need to watch for in these patients. If at all they have any, they do untreated eosinophilic lung disease have various complications like acute eosinophilic pneumonia. If untreated leads to respiratory failure, it can be fatal. Untreated ABPA, untreated chronic eosinophilic pneumonia can cause lung destruction like ABPA is an airway. So there is a destruction of airway leading to bronchectasis. Eosinophilic pneumonia, there is sparenchymal involvement, so there will be fibrosis. So untreated can lead to mortality as well as long-term morbidity in the form of bronchectasis fibrosis. Great. So this has been a very good discussion, Srinath. Very well summarized and explained for our listeners. So before we wrap up, I just wanted to ask you for any take-home messages for the clinicians, for our undergraduates. So a take-home message for the students and our listeners. Take-home message will be always check peripheral eosinophilic counts in unexplained lung diseases. For our physician, practicing in India, asthma will be the most common airway disease that you will encounter. But always remember that there are some things which are not, which points your diagnosis away from asthma, especially when the patient has productive, it takes your diagnosis away from asthma, more towards ABPA. Asthma should have a normal chest x-ray. So if there is any lung findings, is there any x-ray, x-ray findings, always look for other conditions like ABPA, EGPA or chronic eosinophilic pneumonia. And peripheral eosinophilia. Asthma has peripheral eosinophilia but rarely exceeds a level of 1000 or 1500. So very high peripheral eosinophilia, like more than 1500 per microliter, we should always consider other things, especially eosinophilia pneumonia, ABPAs, EGPAs. So it is very, we should have a high index of suspicion, especially in patients with unexplained lung infiltrates and respiratory failure with very uncontrolled asthma, despite optimization of inhaler therapy. And steroids are a effective treatment. So if the patient doesn't, eosinophilia pneumonia is there, doesn't respond to the steroid, that should take your diagnosis to something else. And there should be a good long-term follow-up because these diseases are known to relapse. Even though they respond well to the steroid, they are very much known to relapse, especially chronic eosinophilia pneumonia, ABPAs. That would be my key components. Yeah, so truly insightful discussion, Srinath. And thank you once again for joining us today. And I hope our listeners found this discussion useful and they come back to us with any doubts. If they come back with their doubts and we will definitely get back to you for clarifying those doubts of our listeners. So then, dear listeners, that's all for today's episode of Medford AFMC. Stay tuned for more of such interesting discussions. Until next time, stay curious, keep learning. Thank you once again, Srinath, for joining us. Thank you for having me. I really enjoyed this.