In order to properly discuss or write about some of the more complicated aspects of this disease, I feel I need to try and post as simple an explanation of it as possible. It’s not as simple as I would like because it’s such a complicated set of problems, but I’ve tried to include the basic facts everyone interested should know.
- HLH is a rare disorder of the immune system. It is also commonly referred to as a disease. It’s rarity is currently understood to be approximately 1 in 1 million children.
- There are two forms of the disease. The primary form is FHL, also known as Familial HLH. The secondary form is simply known as HLH. Both forms are treated in the same manner medically, with the exception of the additional need for a Bone Marrow or Stem Cell transplant to cure the primary form.
- When the body has an infection, certain specialized cells activate and fight off the infection. These cells are part of our Immune System. Among these cells are T-Cells and Histiocytes, which when activated cause an inflammatory reaction in the body.
- In most people when an infection(a cold, flu, other virus or a bacterial infection for example) has been eliminated, the inflammatory reaction that helps eliminate them is turned off and the Immune System returns to it’s “Steady State” or normal state. In HLH patients, the inflammatory reaction does not turn off and causes the symptoms of HLH.
- Our Bone Marrow produces our blood cells, including infection fighting cells. As the inflammation persists abnormally, the Histiocyte cells attack or “eat” the other blood cells in the bone marrow, causing a severe drop in cell counts. This means that the patient is exposed to normal infections, but has no way to fight those infections off.
- Typical symptoms of HLH itself can include: Fever, Pallor, Jaundice, Liver and Spleen enlargement, and Neurological symptoms such as irritability and seizures. Not all symptoms appear in all patients initially.
- Because symptoms vary widely and can be associated with other infections, HLH is very difficult to diagnose. It is an especially dangerous disease undiagnosed, with a fatality rate of 100% over a course of approximately 2 months. 100% of patients will die in 2 months if untreated.
- Patients have a better chance of survival of this disease the earlier they are diagnosed and treated. The longer the disease continues, the more damage the body does to itself. Because the treatment itself is hard on the body and the disease often affects young children, if the body is too badly damaged, recovery can be difficult even when treated properly.
- HLH is treated with a protocol or treatment program called HLH-2004. This program was created by an international team of doctors in 2004 to attempt to address the poor survival rates of patients with HLH. Prior to that point, a program known as HLH-94 was used.
- HLH-2004 involves a chemotherapy regimen (a set medicines given to the patient) to stop or suppress the inflammation in the body, bringing the disease under control.
- Once the disease is under control — once the immune system has “cooled off” — symptoms can begin to fade and the patient’s immediate danger from HLH itself is lessened. The patient is still at very high risk from normal infections due to the damaged immune system.
- Infection presents the greatest risk to patients with HLH after it has been diagnosed and treated.
- In the primary form of HLH, known as FHL, remission is only temporary. A Bone Marrow or Stem Cell transplantation is required for long term survival.
- In the secondary form of HLH, the disease can be permanently resolved with the HLH-2004 program in some cases.
The question many parents want an answer to most, “what are our chances”, is very hard to answer. I know I spent a lot of time trying.
That answer is there is no easy answer. It depends strongly on how early diagnosis and treatment took place and what underlying conditions are present. In short: your doctor should be the one to even try to answer that because it really is dependent on the unique situation of each child.
More information is available at Histiocyte.org as a starting point. I’ve posted articles I’ve found to be useful in the Links section above as well.
Well done, as usual, Evan. I think of Zoe as one in a million in all ways, and I have continuing optimism that she will get through these rigorous treatments and a BMT [if needed] with as few complications as possible, and thrive and develop beautifully all along the way.
It is impossible to figure out the answer to the question of why did this happen to her. But it did, and you, Michelle and your families are managing it all with great love, brains, careful attention, and advocacy.
I’m putting up a few informational posts both for those interested, and for those finding this site via searches. Some of this information is scattered about and hard to find or hidden behind for-pay medical journal websites, so I’m trying to collect as much clear info as I can here.
Will return to Zoe pictures and more personal info soon! 🙂
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This really helps us to somewhat understand this confusing disease, Thank You. We are following the progress closely and appreciate the updates. We are certainly praying for a successful and permanent treatment outcome. John
Kia,was initally diagnosed the middle of June2010. she was in remission for about 6weeks.She needs a bone marrow transplant,the doctors say it us not the familal type of HLH.She is 5years old. Praying her sister(who is younger) is a match or her parents
Aimee my little sister was diagnosed with HLH the secondary type, she didnt make it the chemotherapy damaged her heart but atleast i know now what type of disease hurt my little sister and to be aware of this horrible disease. Thank you so much for youre information…………..