CME Slides Forum - M. Skinner

A joint Congress by ERA-EDTA and ISN

NATURAL COURSE AND PERSPECTIVES FOR MEDICAL THERAPY IN AA AMYLOIDOSIS

Martha Skinner, Boston, USA

Chair: Helen J. Lachmann, London, UK

Giampaolo Merlini, Pavia, Italy

Dr. Martha Skinner
Amyloid Treatment and Research Program
Boston University School of Medicine
Boston, USA

Thank you Doctor Merlini and Doctor Lachmann and good morning Ladies and Gentlemen. I’m another member of the Boston Amyloid Group and we’re going to switch gears. We’ve been talking about the most common type of systemic amyloidosis. Now we will switch to the most uncommon type.

So in the AA type of amyloidosis we’re going to this morning talk a little bit about the history and the course and then making the correct diagnosis which is not always easy and the current medical therapy.

Amyloid was discovered about 150 years ago by the famous pathologist Virchow and then 70 years later another famous pathologist Bennhold discovered that amyloid took up Congo red stain and had a beautiful green birefringence under polarising microscopy and that has been the gold standard test for the diagnosis for amyloidosis since then.

The third key discovery in my mind was the amyloid fibril ultrastructure by electron microscopy and that finding allowed amyloid deposits to be isolated form tissue because you could see what they were and then be biochemically identified.

So, the AL that we have been discussing this morning is amyloid of light chain type and is the predominant type of amyloidosis for all the systemic types.
The ATTR, the amyloid of the transthyretin type that is of a mutant transthyretin type is the type in about 10% of patients. Whereas, the AA type, the secondary type related to a chronic disease is probably 1% or less of all amyloid types.

In AA-amyloidosis you need inflammation to start the process, often it is severe and often it is of long duration. As opposed to the AA amyloid or to the AL amyloid AA type takes a long time to develop and is very slowly progressing. So inflammation causes elevation of cytokines, IL-1, IL-6, TNF which act on the liver to produce the acute phase protein SAA.
In some people, not all, in some people who have very severe longstanding inflammation AA amyloid fibrils will develop.

Now, how to make the correct diagnosis and differentiate which type your patient has? Of course, the tissue biopsy is necessary to determine that there is amyloid at all.

Here you can see the favourite screening test which is an abdominal fat aspirate but actually any type of tissue biopsy can make the diagnosis of amyloid. So here fat is placed on a slide stained with Conge red and you can see the example of the beautiful green birefringence that is shown by polarising microscopy.

So the second step in making the correct diagnosis is to rule out the most common types to be sure that the patient doesn’t have AL and just happen to have a chronic infection and doesn’t have ATTR.
The first steps would be to check the bone marrow and check the serum and urine immunofixation electrophoresis to determine whether or not there is a monoclonal light chain. Then if there is a question, transthyretin screening test would be done to rule out TTR amyloid.

So, once the AL and TTR types are ruled out you can focus on the more rare types and to confirm AA-amyloidosis the techniques are not quite as definitive as they are for the other types but one must do immunohistochemical staining of a tissue section with antibody to AA protein.

Here I’m showing you a kidney biopsy from a person with AA-amyloid and you can see on the left the Congo red stained specimen. This particular kidney biopsy didn’t happen to have any glomeruli in it but it did have a number of blood vessels, a band of blood vessels here and you can see how they’ve taken up the Congo red stain and that band of blood vessels has the green birefringence on polarisation.

So to show you some of the difficulties here is the immunohistochemical staining with antibody to lambda light chain and it was similar with kappa and antibody to AA. You can see what looks like a positive reaction which is actually in the tubules of the kidneys above and below this band of blood vessels and here with the antibody to AA we can see the positive reaction in the blood vessels but a negative reaction in the tubules. This is a patient that had severe nephrotic syndrome. The tubules were reabsorbing the protein that was being lost and therefore, the positivity with the anti-lambda stain which was not in the amyloid deposit but in the tubules. So you can see that there is some interpretative skill required in making this diagnosis.

So once you have done the immunohistochemical staining and you feel that it is AA-amyloid, it might be necessary to rule out some rare inherited forms. Some of the rare forms of amyloid do have kidney involvement; so ApoA1, ApoA2, fibrinogen and lysozyme. They may begin as renal disease.

So, if there is any question, you should rule those out at this point. But lastly and I think perhaps almost most importantly, it’s important that the clinical picture fits the laboratory diagnosis. I can’t stress this enough. Determining the amyloid type is a bit of a puzzle and you need all the pieces in place to make that final decision. So by the clinical picture I mean what is the age of the patient? Keep in mind that AA-amyloid can occur in all ages but is probably the only amyloid type in the very young individuals. Keep in mind too that the presentation of the disease if the amyloid has a renal presentation, then that definitely goes along with AA-amyloid. Although some presentations can be autonomic neuropathy and some can be hepatomegaly the most common presentation is a renal presentation.
Thirdly in the clinical picture is there an underlying disease? Is there something that could have caused it? Is it severe enough and is it prolonged enough that it could have led to AA-amyloidosis?

Now, in illustrating this I want to present the case of a young girl that we saw recently, a 17-year old girl from Ecuador who came to us with severe nephrotic syndrome of about 11g of protein//24 hours. She also had severe orthostasis and severe diarrhoea and her kidney biopsy back home had been positive for amyloid by Congo red staining. That was actually the kidney biopsy that I showed you. On our histochemical examination we felt that she had AA-amyloidosis. She did not have a plasma cell dysplasia. She did not have any underlying inflammatory disease. She didn’t have arthritis, she didn’t have bowel disease, she didn’t have any chronic infection that we could determine but she did have very elevated inflammatory markers.

We went on to do a CT of her abdomen and found a 3 cm mass at the gastro-hepatic junction. When this was removed, there was a huge crust of amyloid circulating this B cell mass. Our pathologists thought it had been there for some time because of the crust of amyloid.

At microscopy there was still a lot of amyloid depositing, here you can see these homogeneous eosinophilic appearing areas and there was an atrophic germinal centre, actually a number of them and our pathologist concluded this was Castleman’s disease, perhaps an atypical Castleman’s disease because there was so much amyloid in the tissue he couldn’t see the usual hyaline lines that occur.

Now, as it would come about Doctor Lachmann actually and her co-authors had a very key paper published in the quarterly journal of medicine on unicentric Castleman’s disease which complicated systemic amyloidosis. In that paper she presented 5 patients that were of relatively young age and they presented similarly to our patient with anaemia and acute phase response in nephrotic syndrome. On scanning they were found to have tumours either in the mediastinum, mesentery or retroperitoneal areas that turned out to be unicentric Castleman’s tumours.
Once they were removed, their disease regressed. A very key part of her paper to me was that 20% of the patients with AA-amyloidosis that were of unknown of underlying disease, and they’re in the London series, were found to have Castleman’s disease.

In the few minutes left I want to show you the Boston experience with AA-amyloidosis and I have divided this into two groups: the patients that we saw between 1972 and 1996 and then those seen in the last 12 years. I want you to note at the bottom the ends. So in the first time period out of 810 patients altogether, 99 had the AA type of amyloidosis and in the recent experience out of 1800 only 48. You can also see that infections were a common aetiology in the initial group and since that they have gone down tremendously.
Rheumatologic and inflammatory bowel disease and FMF still persist to some extent although much fewer because of the low end that we have but we do have patients of undone aetiology. We’re now able to determine some patients that have AA-amyloid without an obvious underlying disease. Some of them likely have Castleman’s disease.

So is AA-amyloidosis disappearing? I think it is, yes. Is it underdiagnosed? Maybe to some extent.

When we look back at 1972 probably 20-40% of patients with leprosy died of amyloid disease. Chronic TB was a prominent cause

and since then there are major treatments that cure or tremendously decrease these diseases.

and in 1974 colchicine was found to be a treatment for FMF and since then AA-amyloidosis and FMF is quite rare.

Treatment for rheumatologic and for inflammatory bowel diseases have become more effective and in recent years fewer patients develop AA-amyloidosis.

So for the AA-amyloid due to infection or inflammation, infectious diseases have nearly disappeared except in underdeveloped countries. Inflammatory diseases and treatments are much, much better and in some cases other causes are being found that we need to be alert to.

The treatment targets for AA-amyloidosis are really two. What can be done about the inflammation so that the SAA level does not become elevated? What can be done to prevent the AA-amyloid from being deposited?

We’ve talked about anti-inflammatory medications. There’s surgical removal of an inflammatory stimulus that can help at the first site and there is due to begin a clinical trial, a second clinical trial actually on the drug eprodsate which may help to prevent AA-amyloid deposits from occurring.

So in summary, major treatment unfortunately, there is no specific treatment at the present time for AA-amyloidosis other than removing the inflammatory stimulus where it’s possible to do that and hope the second clinical trial will take place.

Lastly I’d like to remind you that supportive treatment for these patients is of key importance. Their course is long, they don’t have a short survival like AL-amyloidosis but they often live for several years and some supportive treatment can actually be lifesaving. Renal disease is a prominent manifestation. A number of patients can be treated with dialysis if they reach end stage disease and can have kidney transplants when it’s appropriate and for autonomic neuropathy and for severe diarrheal there are things to do to make life better.
Thank you.

Chairman: Thank you Martha for this brilliant presentation and it’s open for discussion. Please?

Question: Thank you for the excellent overview. If you’re obtaining bone marrow biopsies from AA-amyloid patients, it is wise to stain immunohistochemically the bone marrow and you get rid of the sticky proteins which are present in the tubules and your diagnosis in terms of immunohistochemistry may be more specific. I think it would be wise to include the genetic tests which are done today for auto-inflammatory syndromes including FMF in the differential diagnosis.

Question: Martha I have a question. The difference in incidence in AA-amyloidosis between the United States and Europe is striking and I have to confess post clinical London isn’t great but we aren’t yet the developing world and 15% of our systemic amyloid is AA. Do you have any theories about why there is such a major difference between Northern Europe and United States in the incidence of this?

Dr. Skinner: I’m shocked to hear the 15% because I don’t have an idea as to why that is and I think it’s an astounding figure and I’m wondering why you couldn’t fill up the clinical trial for Kiacta with all those patients.