Malignant Psoas Syndrome

Malignant psoas syndrome is said to be extremely rare, but I keep seeing it. Admittedly, working in the pain and palliative care service in a specialist cancer centre, if anyone was going to see it, you would think it would be my team.

I have had three patients with MPS this year and because each time it’s something that the clinical staff are not familiar with, I thought I would share a  short summary with the Palliverse.

The original description of MPS in 1990 (1) described patients with:

  1. Metastatic cancer involving the psoas major muscle either intrinsically (direct intramuscular metastasis), or extrinsically from metastatic retroperitoneal lymph- adenopathy infiltrating into the muscle.
  2. Painful flexion of the ipsilateral hip with positive psoas stretch test (‘‘reverse’’ straight leg raise) related to psoas muscle spasm or irritation.
  3. Clinical evidence of proximal (L1–L4) lumbar plexopathy with spontaneous, burning and lancinating pain associated with hyperalgesia (allodynia and hyperesthesia).
  4. Absence of osseous lumbar vertebral metastases and/or concomitant lumbar polyradiculopathy due to other causes (e.g., malignant neuraxial dissemination, chemotherapy-associated or radiation-induced neurotoxicity).

In 2010, Stevens et al wrote a helpful review (2) of MPS with a case review, mechanisms and theories. Five years ago, according to the paper, there had only been 28 cases reported in the English speaking literature.

I will leave interested readers to explore the papers themselves, but it describes polymodal pharmacotherapy (aka throw everything at it), plus some novel strategies like local anaesthetic block of psoas sheath.

What has encouraged me to put fingers to keyboards tonight though is the referral of yet another patient with psoas syndrome, plus this Japanese case series by Takase et al (3). It describes three patients with MPS who had excellent results with methadone (15-30 mg/day). Their average pain scores were reduced by an astounding 7 points with greatly improved function.

I am pretty keen to try adjuvant methadone for my new referral.

Have you seen any malignant psoas syndrome cases before?Were they recognised and treated as such? How did it go? Particularly keen to hear whether anyone has tried methadone. 



1. Stevens MJ, Gonet YM: Malignant psoas syndrome: Recognition of an oncologic entity. Australas Radiol 1990; 34:150–154.

2. Mark John Stevens, Charlotte Atkinson, and Andrew M. Broadbent. Journal of Palliative Medicine. February 2010, 13(2): 211-216. doi:10.1089/jpm.2009.0193.

3. Takase Naoto, Ikegaki Junichi, Nishimura Harumi, Yuasa Sayoko, Ito Yumiko, and Kizawa Yoshiyuki. Journal of Palliative Medicine. July 2015, 18(7): 645-652. doi:10.1089/jpm.2014.0387.

5 thoughts on “Malignant Psoas Syndrome

  1. Hi Sonia,
    Thanks for the great post.
    I don’t think I have ever identified a patient with MPS in my practice, but your post certainly got me wondering about a number of patients with advanced cancer and complex lumbar neuropathic pain. All those cases where in a hospice setting and my memory is that we used the “throw everything at it” method. I can’t remember whether we tried methadone, but it would seem a reasonable thing to try to me. I will certainly keep your post in mind next time I see a case.


  2. HI:

    I had perennial sarcoma 3 years ago and it looks to be back on the Psoas muscle. The MRI seems to describe it as a re-occurrence. How do you determine weather it is sarcoma again or Malignant Psoas Syndrome?


    • Hi Vrej, I am sorry to hear that.
      Malignant psoas syndrome refers to a group of signs and symptoms (eg. pain) that occurs when there is a cancer in the psoas muscle.
      The diagnosis of a recurrence of the sarcoma would likely be best made with an MRI. If confirmation is needed, your team might talk to you about a biopsy.
      So, if you have a recurrence in the psoas muscle and have symptoms consisted with malignant psoas syndromw, you could have both. Can you discuss with your doctor?


  3. It has been years since this was posted but I wanted to share my experience with this, I was in a lot of pain for months and going to physical therapy chiropractors and so on, even hospitalized for anaemia and also the pain and it was a while before my psoas mass was identified, it was a 7 mm mass I believe, and it was very painful for months, only on left side, I assumed it was sciatica and piriformis was also suspected among other things. It was a metastasis of my endometrial cancer, it was quite advanced when I was diagnosed but the radiation helped the pain greatly and I’m now undergoing chemo. It’s been quite the journey and it’s a symptom my oncologists said she doesn’t see often


    • Hi Tia, You are right, it has been a long time, but I am still seeing it a few times a year! I am glad to hear your pain is better than it was, I hope the radiation and chemotherapy continue to help.


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