AVM Survivors Network

STS Foam Sclerotherapy

Hello All,

A bit of background always helps. I’m 29 and I have a VM in my bottocks. It’s pale blue on one cheek and about 4 inches in length, but of course it’s larger than that since it’s internal as well. I’d say that I’m luckier than most here, since I’ve been symptom free until about the age of 25. In fact, I was under the impression that it was simply skin discoloration and that my bowel problems were related to hemorrhoids. My only symptoms today are intermittent pain and having to squat during bowel movements. I’m pain free for most of the year, sometimes I’ll get pain when standing or sitting for very long periods of time (like a concert, or extended walking during a vacation), but every once in a while I’ll have daily pain lasting for a couple of months. I’ve attributed the pain to phleboliths, which are calcified blood clots.

Earlier this year I was in significant enough pain to contact a local interventional radiologist and he scheduled me in for STS foam sclerotherapy. I’d love to be able to reduce the size of the VM, even just to have proper bowel movements, but I’m having second thoughts. I can currently live with this thing the way it is, but I know that blood vessels only get worse with age, so I’ll eventually need this procedure, but my worry is that there’s a chance that the sclerotherapy could somehow make it worse. I certainly would not like to turn an intermittent pain situation into a chronic one.

Can anyone here share there experiences regarding this procedure? Am I being paranoid with regards to negtive outcomes? How long does it take until the post-procedure swelling diminishes and you’re able to gauge its effectiveness? I have no problem if the procedure does nothing for me, but making it worse and giving me chronic pain would wreck havoc on my mental state, especially considering this is an elective procedure.

Thanks for reading.


I believe this may be your first post so welcome! If it isn’t, plea ignore me! I had a brain AVM, so can’t really pass along any much experience. Just a quick welcome!


Welcome! It’s good to hear from you and I’m really interested by the concept of phelboliths! Never heard of those before but they do sound relevant to this community. Like John, I’m a brain AVMer but we do have an active contingent of @Extremity AVMers with whom I think you’ll have more in common and some also have an AVM in the same place.

Very best wishes,


Hi there, I too have pheboliths in my arm and have had diffuse VM and AVM in my left arm since childhood. I have been living this way for years and I did not get updated opinions for a long time, but earlier this year, I talked to a multi diciplinary team about my problems to get updated opinions because my wrist and fore arm were getting puffier. I was told after years of docs in Boston when I was a child telling me that I have lymphatic malformation that I have AVM and VM in the arm.
The summation of my second opinion visit with the team at USC (who treat children out of LA’s Children’s hospital, but see adults on an advisory basis). They described dealing with AVM as a game of chess and that if you can live with symptoms sometimes doing nothing is the answer. I think for me, since the VM and AVM material is in my arm and not going to interfere with anything or become life or limb threatening and that I have been living this way for so long, we decided to leave the problem be and wear compression and take asprin therapy. My problem might be more diffuse than yours. My question to you is have they done any imaging of your buttocks yet? Is it more superficial or bigger? I only ask because you mention your pain and problems with standing, going to the bathroom, etc. Has it been pretty much the same as always or has it gotten worse? If the problem is more internal, you might want to be evaluated by a multi diciplinary team. Just to give you an idea, I saw a orthopedist specializing in tumors and lesions, vascular surgeon, and then went to a vascular anomalies team at another hospital for a second opinion. The ortho surgeon (ortho oncology specialist) also sent me to the oncologist to talk about the new findings in targeted cancer drugs to treat AVM, but this track was too out there for me. There are findings that the MEK inhibitors can also help with AVM if it is a match. The oncologist said he would not consider giving me the drugs because again my AVM is not life threatening. He did offer another drug that is an anti angiogenisis drug, but that seemed like overtreating the problem with the amount of side effects. I would only consider taking those drugs if my avm was interering with my general health. You have to use your best judgment, but def find people specializing in this. I just want to clarify that my case involved joint issues and might be more complecated than yours. My understanding is if your AVM is just in one specific area, the embolization could be a good approach. I have been told though that procedures (such as the elbow joint surgery I was considering) could “stir up” the AVM. The major outcome I am trying to avoid is the avm in my wrist getting into my hand.

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I also wanted to state that a compression sleeve has helped with my pain and discomfort immensely I don’t take nearly as many ibuprofins or Aleves as I used to. I know that folks have mixed reviews on this, but it really helps me during the day. I don’t wear it at night, but I was told by the folks at USC to try to. I have an older more streched sleeve that I have started wearing at night as well when I remember to.

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Hello All,

Thanks for all your replies. I’ve had a busy week so I’m just now able to respond to all of you.

@JD12 @DickD

Thank you both for the kind welcome.


I’ve been researching vascular malformations for a few years now. I’ve read pretty much every relevant published paper on the topic and I have a science background which has helped in digesting and making sense of the information. I’m not a doctor, but I think I have a fairly good understanding of the underpinnings of these groups of genetic diseases.

Phleboliths are calcified blood clots. They are typical in low-flow vascular malformations called venous malformations (which are purely venous, as opposed to arteriovenous). They occur due to stagnant blood pooling in the malformed venous channels which results in thrombosis. Symptoms are more typical in winter months when blood circulation slows at the extremities due to higher blood viscosity from lower external temperatures. Since AVM’s are high-flow malformations, this is less of a concern.


Thanks for your reply. I am being seen by an interdisciplinary team which specializes in interventional radiology for venous and arterialvenous malformations. My condition is the former, purely venous. It presents as a focal bluish superficial lesion on the skin and extends into my butt cheek, however it is not particularly diffuse but more well-defined with large venous channels. It’s more localized and does not involve any of the major veins in my circulatory system. In MRI, it’s shown as having well defined boundaries with a small diffused section running down my buttcheeck near my sphincter, which causes my bowel problems. It has not been formerly classified, however I believe it’s close to a Grade 2A which is well defined, >5cm diameter.

With regards to inhibitors, I have read extensively about the pathways associated with malformations. The proper umbrella term for our conditions is congenital overgrowth syndromes. There are two genetic pathways primarily associated with overgrowth syndromes. The mTOR pathway and the MAPK1 pathway. You can see these pathways here https://imgur.com/orIJCXY. Both of these pathways regulate cell transcription. In purely venous malformations (VMs), the genetic pathway is associated with the mTOR (mechanistic target of rapamycin) complex. People with VMs (like myself) can have one of two mutations:

  1. A somatic mutation in the TEK gene which encodes the tyrosine kinase receptor TIE2 which affects the PI3K/AKT signaling pathway (this is the most common mutation in unifocal malformations);
  2. A somatic mutation in PIK3CA itself (which is more downstream from TEK). Some people with a mutation in PIK3CA can be grouped into a disease spectrum called PIK3CA-related overgrowth spectrum (PROS). There are many disorders under PROS which include: CLOVES, Klippel-Trenaunay syndrome (KTS), and Lymphatic Malformations (LM).

In both cases, the underlying mechanism of overgrowth is due to a high gain feedback-loop in the PI3K/AKT pathway which is associated with mTOR. This pathway is very interesting. mTOR is called a growth signalling molecule. It sits in the lysosome of cells and waits for signals from the body to begin the growth process. When people eat: proteins, nutrients and hormones (like insulin) pass into the cells and ‘turn on’ mTOR which tells the body to begin using energy for growth. When people fast (long periods of time without food) the body shuts down mTOR and begins the process of autophagy (cell death) in order to consume itself for energy. In venous malformations, this process is always turned on in the malformed cells. This is why malformations have growth spurts during periods of development (such as puberty or during pregnancy) because the body is flooded with growth signaling hormones.

Rapamycin (sirolimus) can prevent the growth during these stages, however it has a smaller effect on malformations that have already grown. It does provide some relief here, but not nearly as much as in these growth stages. However it’s being shown that Rapamycin + Ponatinib can cause regression in already developed venous malformations, so there is some hope that in the future people will be able to take these drugs and reduce the size of their malformations without sclerotherapy. The nice thing about these drugs is that a small amount can have a profound impact on the signaling pathway while leaving healthy cells mostly untouched.

As for arteriovenous malformations (AVM) they involve a different genetic pathway. AVM’s typically have one of two mutations:

  1. somatic mutation in the Mitogen Activated Protein Kinase (MAP2K1) gene which encodes extracellular signal-regulated kinase 1 (MEK1). This gene, MAP2K1, is also associated with growth factor signaling in the cells. It is part of the MAPK/ERK pathway, which acts as an on/off switch in protein signaling during growth. Similarly to mTOR, this gene is associated with cell transcription and regulation of cells. When this gene malfunctions due to a mutation, it causes overgrowth, particularly in the connections between arteries and veins.
  2. Somatic mutation in HRAS, KRAS or BRAF. These genes are found downstream in the MAPK/ERK pathway. This is analogous to PI3KCA mutations in venous malformations. It’s located more downstream from MAP2K1, but in both cases you have the same general phenotype of overgrowth (physical appearance).

Sometimes VMs have mutations in MAP2K1, and sometimes AVMs have them in TEK, so it’s not a hard rule. Although, all congenital non-familial malformations have the same characteristics. They have a somatic (single) mutation in a gene pathway associated with growth that causes the pathway to be always turned ‘on’, despite a lack of signals from the body.

You’re born with these mutations, so they don’t just arise from chance later in life (as far as I know). When they arise later in life, we call them cancer. This is why cancer drugs are also effective on malformations; because they are both caused by the same pathway. So people with AVMs have always had them, they just present with symptoms at different times, or not at all if it’s minor. If you have one mutation somewhere in your tissue (brain, or elsewhere), it’s not likely that you have any more unless you’re very unlucky, or you have a familial gene mutation which is associated with a broader disorder. In both of our cases, it sounds like we just got unlucky with one mutation in one part of our bodies. Since you have an AVM/VM, it’s very likely that you have a mutation in MAP2K1 rather than in TEK (mTOR).

I’ve done a lot of research so I just wanted to share, especially to the people lurking these forums looking for answers. hope that sheds some light on how this destructive disease is caused. The good news is that both mTOR and MEK inhibitors will work at reducing the size of the malformation. I don’t know about MEK inhibitors, but mTOR inhibitors generally don’t cause too many side-effects and if they do, they are totally reversible when you stop taking them. Luckily for me, my VM is smaller therefore using inhibitors is probably overkill.

Unforunately, I cant wear compressive stockings because of the location of my VM. Whenever I sit, it kind of acts like a compressive stocking because it compresses the VM. Once I stand, the blood begins to pool in the VM and it enlarges. However I have decided to go ahead with sclerotherapy, so I’ll update this post post-treatment to let you know how it went.

Wow, thanks for the awesome breakdown on the cancer therapies. Just to clarify, my latest report from USC from the intervenional radiologist on their team hypothesizes I have had VM for years in my arm and have somehow “acquired” a AVM down by my wrist. (The wrist symptoms started about a year and a half ago.) I am hopeful the proper drug combination will come out in the next years that could support a remission in the vascular problems and finally allow the joint surgery, but until then just watching and waiting with my assorted compression sleeves!

Good luck in your procedure - sounds like you’re in good hands!