Tuesday, August 27, 2013

The Alphabet Soup of Pulmonary Fibrosis

The Alphabet Soup of PF
It is not surprising that there's a lot of confusion out there about the different kinds of PF. Here's why...
  • There are over 100 different kinds of PF that all look very much alike
  • There is an alphabet soup of confusing and sometimes poorly defined abbreviations for many types of PF (IPF, PF, ILD, NSIP, RB-ILD.... the list goes on and on).
  • Even experts will often disagree about which kind of PF you have.
Experts typically do agree, however, that it is important to try to sort out which kind of PF you have, since different kinds of PF behave differently both in terms of how quickly the disease might progress as well as whether it might respond to medical treatments (such as prednisone). I'll talk about how we sort out which kind of PF is affecting the lungs in future posts. In this post, I'll try to clear up the confusion about the different terms used to describe different kinds (and families) of PF

Pulmonary Fibrosis (PF)
I discussed this a bit in a previous post. PF isn't a single disease -- it's the name of the entire family of diseases that affects the walls of the air sacs (alveoli) of the lungs. This family of diseases is also sometimes called the Interstitial Lung Diseases (ILDs) -- the medical term for PF. So, Pulmonary Fibrosis = Interstitial Lung Disease. Another name for the ILDs (or for PF) is Diffuse Parenchymal Lung Disease (DPLD).

Idiopathic Pulmonary Fibrosis (IPF)
IPF is one specific kind of PF. The word "idiopathic" means that we don't know the cause of the disease. But we don't use the term IPF to refer to the all-to-common situation of not being able to find a cause for your PF. Instead, we reserve the term IPF for one specific type of PF of unknown cause. 

The fundamental problem in IPF is scarring that occurs in a predictable pattern in the lung. In IPF, scarring begins in the walls of the air sacs just beneath the outer lining of the lung (this outer lining is called the "pleura", so the location of the scarring is called "sub-pleural" by doctors) and predominates in the parts of the lung that are closest to the ground when you are standing up (the so-called "basilar" part of the lungs). So, in IPF, the scarring begins in the walls of subpleural basilar alveoli (hey -- you sound like a doctor now). As the disease progresses, the scar tissue spreads to involve more and more of the lung. Eventually, the lung is mostly replaced by scar tissue. 

Doctors recognize that IPF is present by first noticing the four consequences of PF -- crackles heard in the lungs when your doctor listens to your lungs, stiff lungs detected by pulmonary function testing, low oxygen levels in the blood particularly during exertion, and abnormalities seen on a CAT scan -- that we discussed in a previous post

In the case of IPF, a comprehensive evaluation for known causes of PF is unremarkable. This evaluation includes a lot of questions from your doctor, a physical examination, and typically includes lots of blood tests. 

In addition, in IPF the abnormalities on the CAT scan are often quite characteristic (scar tissue in the subpleural basilar parts of the lungs -- this is called a "usual interstitial pneumonia" or UIP pattern on the CAT scan -- more about this confusing bit of terminology in a future post). 

In many cases, an unremarkable evaluation for known causes of PF combined with a "UIP" pattern on the CAT scan are enough to make the diagnosis of IPF. However, sometimes there is doubt about the appearance of the CAT scan and a surgical biopsy of the lung is required to make the diagnosis.

I'll go into detail about IPF in future posts. 

Idiopathic Interstitial Pneumonia (IIP)
This is another term that isn't a single disease -- just like PF, it refers to a family of conditions. The IIPs are a group of 7 specific types of PF that are grouped together because they are "idiopathic" (of unknown cause). The IIPs are:
  • IPF (idiopathic pulmonary fibrosis)
  • NSIP (non-specific interstitial pneumonia)
  • RB-ILD (respiratory bronchiolitis-associated interstitial lung disease)
  • DIP (desquamative interstitial pneumonia)
  • COP (cryptogenic organizing pneumonia)
  • AIP (acute interstitial pneumonia)
  • LIP (lymphocytic interstitial pneumonia)
I'll talk about the diagnosis, prognosis, and management of IIPs in future posts.

PF of known cause
There are many types of PF that can be traced back to a plausible trigger or risk factor. Some of these are:
  • Medication (drug)-induced 
  • Radiation-induced
  • Occupational causes (so-called "Pneumoconioses")
  • Hypersensitivity Pneumonitis (HP)
  • Autoimmune conditions (such as scleroderma, rheumatoid arthritis, and dermatomyositis)
I'll talk about some of these conditions in future posts.  

Other kinds of PF
There are many other kinds of PF -- too many to list here. Some examples are:
  • Sarcoidosis
  • Pulmonary Langerhans Cell Histiocytosis (PLCH, also called eosinophilic granuloma)
  • Eosinophilic pneumonia
  • Lymphangioleiomyomatosis (LAM)
More to come about PF...  


  1. This post sent me on a google search a I was very interested in "known" causes of PF. In particular I looked up Pneumoconioses and Hypersensitivity Pneumonitis. As it turns out my husband could fall under either one. We've been fighting a losing battle with a leaky basement and although we try to keep on top of any mold growing we suspect that there is mold now under the new flooring we put down in the laundry room (we thought we had the problem fixed). He has also worked for the past 13 years at a large fertilizer (phosphorus) manufacturing site. Although he doesn't work directly in the plant but in a separate building his office windows are all pitted from the "dust" and his vehicle is often covered with it as well. Many a time he can smell the ammonia in the air. Hopefully this information will help our doctor with a more specific diagnosis.

    1. Thanks for sharing your experience. It is not uncommon to find more than one potential contributor to pulmonary fibrosis.

  2. With what I've been reading lately especially regarding MUC5B, Familial Pulmonary Fibrosis (FPF) while classified as IPF may actually be it's own category because its prognosis seems to be different and perhaps the treatments. Is there any consensus on this yet?

    1. Hi Barbara,

      Your question about MUC5B is very insightful. Individual risk factors (such as a MUC5B mutation) might contribute not only to the development of the disease but also to particular characteristics of the condition (such as how rapidly the disease might progress). There is a lot of ongoing research into MUC5B and other risk factors for pulmonary fibrosis -- hopefully we will have a more definitive answer to your question in the coming years.


  3. As I continue to research, read, ask questions, I become more, and more confused. My original chest xray showed reticulonodular, glass opacities diffusely throughout both lungs. The HRCT originally showed fibrosis, with no honeycombing, primarily in my upper lobes. A bronch showed that my upper lungs were the areas most affected. I had two opinions, one at a local pulmonologist, and another at a center of excellence, with a PF specialist. A second battery of all tests, were still inconclusive (all autoimmune/environmental issues ruled out). My biopsy showed most indicative of UIP/IPF. There is a familial trend; mother, brother, sister all died from IPF. Can you address UIP, as well as genetic tendencies??

    1. Thanks for sharing your experience. Yes, I will certainly discuss UIP and genetic contributions in an upcoming post. Best of luck!


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  5. Is it normal for people with PF to get phlegm in the throat and it not go away? At first I thought it was from a sinus infection but that is not the case per my regular doctor. I know you cant give a diagnoses, but was wondering if it is part of having PF?

    1. Thanks for you comment, and I apologize for the delay in answering you. I have found that most of my patients with Pulmonary Fibrosis have exactly the same symptom that you describe -- bothersome phlegm in the throat. In most cases, this is due to either post-nasal drip or from irritation of the throat from gastroesophageal reflux traveling up to the throat -- this is called laryngopharyngeal reflux (LPR). If you do have post-nasal drip or LPR, there may be some straightforward treatments that your doctors can recommend.

    2. My husband has IPF, and each morning after he gets up he coughs for probably 20-30 minutes trying to get the phlegm out. He has one of these coughing spells again after any exercise and usually again before bed. It is truly debilitating. On 12/3/14 he had his first appointment with the ILD group at UAB. As others have said, his local pulmonologist didn't have a clue about IPF. We certainly wish we had gone to UAB sooner. We have had 2 initial appointments at UAB, but we return on 1/20/15 to finally see the physician who will be in charge of his care. Your post gives me hope that perhaps they can do something to make this cough better. After his 2nd appointment (on 12/29/14) they started him on 20 mg of prednisone because his Sed rate and CRP are high. They tested bunches of other antibodies, and they were all normal. I think the prednisone gave him more energy but unfortunately did not help the cough. He has type 2 diabetes, and the prednisone was really bad for his blood sugar. He's supposed to call the nurse practitioner tomorrow to report his results, and I think they'll start taking him off it. Thanks for your info.

    3. Good day i just want to,know if you got to the problem for this cought mine is exacly the same and no,dr,can sort it out thanks

  6. is patient with non specific pf benifitted by prednisne.....or should repeat the biopsy fr rx plan review,,kindly reply,,my mother is suffering from NSIPF.......she is 54 yrs,on prednisone 5 mg, pirfinex,mucinac since 1 & half yr...

    1. Thanks for your question. Unfortunately, I am unable to comment specifically on anyone's medical condition unless they are a patient under my care. I do recommend that you ensure that your mother is seeing a physician who specializes in the care of patients with Pulmonary Fibrosis. The Pulmonary Fibrosis Foundation has a terrific website that may be helpful: http://www.pulmonaryfibrosis.org/MedicalCenters

  7. My husband has IPF he was diagnosed in Dec 2011, now on Oxygen 24/7 and getting increasingly breathless on an exertion at all. His Father was diagnosed with Sarcoidosis in 1988 and died in 1990. My question is could this be related to my husbands IPF or possibly did his Father have IPF and should I talk to his brothers and my Children about getting themselves assessed.

    1. Hi Theresa,

      Thanks you for your question. There is a possibility that your husband's lung disease is linked to your father-in-law's lung disease. I suggest that you and your husband talk to your husband's pulmonologist about this possibility, since he or she will have access to the medical details of your husband's condition.

      Your question about the possibility of other family members being affected by PF is an important one. The chance of other family members developing PF is very low, but it is not zero since there are some types of PF that run in families (called Familial Pulmonary Fibrosis, or FPF). You can consider reaching out to the FPF Genetic Counseling Center at National Jewish Hospital in Denver, Colorado. They offer some services over the phone. Their website is http://www.nationaljewish.org/programs/directory/fpf-genetic-counseling.

      All the best,
      David Lederer

  8. Thanks for all your good work.

    Why are all clinical trials and new medicines apparently exclusively for the benefit of IPF patients? I have cellular/fibrotic NSIP. Six months ago my doctor told me that according to GAP I had a 39% one-year life expectancy. I've tried everything available. All the trials and new drugs are limited to IPF patients. Is there any hope for folks like me?


    1. Hi Tom,

      I understand your frustration. As far as I can see, there are no clinical trials for folks with "idiopathic" cellular and fibrosis NSIP. The good news is that in general, people with a "cellular" (or inflammatory) part of their NSIP tend to do better in the long-run than people with IPF -- so the GAP score (which was developed for people with IPF) may not entirely apply to you. I also never know how to interpret a prognosis like "39%" -- are you going to be one of the 39% or one of the 61%?? Be sure to talk to your doctor about medications that might help treat the "cellular" part of your lung disease. Also discuss whether or not your disease has an underlying identifying cause (such as an autoimmune condition) -- if it does, then treating that condition can also be helpful.

      All the best!

      Dave Lederer

  9. Dear Dr. Lederer,

    Thanks a lot for taking the time to reply. Just knowing that the GAP program was written for IPF and not necessarily NSIP has made my evening! I'm comfortable with the idea of dying, but knowing that my odds may be a little better than I thought is a nice early Christmas present.

    I wish you and your family a healthy and happy 2016.


  10. In 2009, I was diagnosed with NSIP, by biopsy, already had asthma. I was put on higher dose meds for GERD and kept on my asthma meds. I did well until about three months ago. Since then, I've had one infection after another. Once a month on average, I have been on a strong, 10 day course of steroids.I just finished the last course and still feel pain and congestion when breathing at rest. My doctor has not done any new diagnostic tests yet. I wonder if he should? Also, I used to have Discoid Lupus for about 9 mos, and wonder if I should be tested for Lupus?

    1. I am sorry to hear you are suffering from all of those infections! It is hard for me to say what your doctor should do. In general, it is reasonable to look for causes of NSIP -- bloodwork can help. So can reviewing thorough list of symptoms and exposures -- and a careful physical exam by your doctor. Wishing you all the best.

  11. Dear Dr Lederer
    My mother passed away from IPF several years ago, she always seemed to have a mild cough for years before her diagnosis, she started to get more and more breathless and then is was discovered she had the horrid disease, my Mum never smoked and was a very healthy woman all her life. My Gran mother also passed away with this disease and recently my Mothers younger sister who was only in her late 60s passed away with IPF. My question is I am concerned that this is a family gene and i also cough in the morning get breathless climbing stairs, i am very fit and usually put it down to getting old but its always at the back of my mind. some websites say that once diagnosed the life expectancy is only a few years, but can you have IPF for a long time without knowing its there and is there any chance that this disease can be passed down from generation to generation, thank you and i look forward to your reply.

    1. Hi. Thanks for reaching out. I am sorry to hear that your mom passed away from IPF. I hope she didn't suffer too much. Most of the time, IPF is not passed down to children or grandchildren, but sometimes it can be passed down. Even if your mom didn't have IPF, I would suggest you see a doctor to evaluate your cough and your breathlessness with stairs. Usually these symptoms turn out to caused by minor conditions, but it is still important to be seen by your doctor to make sure nothing more serious is going on. All the best.

    2. Thank You Dr Lederer, I will follow your advice and get it checked out. I appreciate your swift reply, I live Ireland and until my mother was diagnosed with IPF myself and my family had not heard of it and it took ages to get a correct diagnosis for my mother. Thank you again and all the best. Laura

  12. I was diagnosed via biopsy in upper, middle and lower left lung with Pulmonary scarring and DIP throughout my lungs. I understood these to be two different dx. Is that the case usually? Does this change prognosis?

  13. Dr. Lederer,

    Are you saying that all of your patients that have IPF have LPR?

    I was recently diagnosed with LPR and I came across an NIH study that said LPR leads to more aspiration and aspiration (with or without acid) leads to IPF.

    I guess I am trying to get a better understanding of my risk for IPF. I know that just because LPR is present in all IPF patients does not mean that all LPR patients will get IPF (or does it).

    I am 25 and am worried about my developing IPF and having a shortened life.