Are Back Mice Real?

Non-specificity of the condition may lead to misdiagnosis

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Back mice is a colloquial term used to describe painful bumps in and around the hips, sacrum, and lower back. It's not a medical term but one that people apply to many different conditions. It involves a fatty lump in or around the back and spine.

The term is used more by chiropractors than other healthcare providers. Some argue that the non-specificity of the description may lead to misdiagnoses and incorrect treatment if the underlying causes are not properly investigated.

This article looks at what back mice are, the conditions linked to them, their symptoms, and how they're diagnosed and treated.

Potential causes of back mice.

Lara Antal / Verywell

What Are Back Mice?

Back mice were first described in medical literature 1937 when a healthcare provider named Emil Reis used the term in association with a condition called episacroiliac lipoma.

Since then, many conditions have been associated with back mice. These include:

You can often see the lumps under the skin.

What Are Back Mice?

Back mice is a term used to describe painful masses of fat that protrude (herniate) through the lumbodorsal fascia which covers the deep muscles of the low and middle back.

Symptoms

These fat masses tend to have a firm, rubbery quality to them. You might find them on the hip bones and sacroiliac region.

Back mice move under your skin. They're often found by chiropractors and massage therapists during routine treatments.

Besides being unsightly, back mice often cause excruciating pain. That's most often related to placing pressure on nerves or damage to the underlying fascia. (Fascia is a thin connective tissue that surrounds most of your muscles and organs.)

Back mice are typically tender to touch and can make it hard to sit in a chair or lie on your back.

Diagnosis

Because of how non-specific they are, healthcare providers sometimes diagnose back mice by injecting the lump with a local anesthetic. If it relieves the pain, the lump is likely a back mouse.

This is a problematic means of making a diagnosis. Giving a local anesthetic, by its nature, will relieve nerve sensations and therefore pain. So it's proof of pain but not necessarily of the pain's cause.

An abnormal fatty growth should never be diagnosed by a chiropractor. Rather, it should be looked at by a qualified dermatologist or medical professional who can perform imaging studies and a biopsy if needed.

The fatty deposits can be any number of things, some serious and others not. The same applies to the sources of nerve pain. While a lipoma/back mouse is the most obvious explanation, others include:

  • Sebaceous cysts: A benign, fluid-filled capsule between layers of skin
  • Subcutaneous abscess: A collection of pus beneath the skin; often painful, may become red or inflamed
  • Sciatica: Radiating nerve pain down one or both legs caused by a herniated disc or a bone spur in the lower back
  • Liposarcoma: Malignant tumors that sometimes appear as fatty growths in the muscles

Painful lipomas are also associated with fibromyalgia, a chronic condition that involves abnormal pain signals.

Recap

Back mice are painful lumps in the lower back and hip area. They're rubbery, fatty lumps (lipomas) caused by several different conditions. They move under the skin when poked.

Back mice can cause pain by compressing nerves or damaging fascia. The pain can be severe.

They're often diagnosed after being injected with an anesthetic. If the pain goes away, it's a back mouse.


lipomas on lower back
Lipomas on lower back.

DermNet / CC BY-NC-ND

Treatment

Unless pain is unmanageable, a back mouse usually doesn't require treatment. They should be checked, though, to make sure they're not cancerous.

Treatment usually involves injected anesthetics, such as lidocaine or corticosteroids. You can also try over-the-counter pain relievers.

If pain is severe, surgical removal may be possible. It involves cutting out the mice and repairing the fascia. This is the only known way to get lasting pain relief.

However, if you have a lot of back mice—some people have hundreds—removal may not be a good option. If the back mice are smaller, more extensive, and more fluid, liposuction may be effective.

Complications of surgical removal include:

  • Scarring
  • Bruising
  • Uneven skin texture
  • Infection

Call your healthcare provider if you experience fever, chills, nausea, increasing pain, bleeding, or discharge.

Complementary and Alternative Treatment

Many chiropractors believe that back mice can be successfully treated with complementary and alternative (CAM) therapies.

A common approach uses acupuncture and spinal manipulation. It's less invasive than standard treatments and is unlikely to harm you.

A 2016 case study reported that the anesthetic injections followed by dry needling (similar to acupuncture) improved pain relief.

Summary

Back mice are painful fatty lumps under the skin. They move if you press on them.

They mostly show up in the lower back and hip area. Technically, they're called lipomas.

Back mice compress nerves and damage your fascia. That can cause severe pain.

Diagnosis can be made by injecting an anesthetic and seeing if the pain goes away. Treatment may involve more injections. If pain is severe and doesn't go away, surgery may be an option.

CAM treatments like acupuncture, dry needling, and spinal manipulation may help.

A Word From Verywell

Anytime you find a lump, you should have your healthcare provider look at it to make sure it's not something serious.

The good news is that back mice don't usually cause major problems. If they do, you have treatment options to explore.

It can take time to find what works for you. Involve your healthcare provider in the process so they can help you find relief.

Frequently Asked Questions

  • What can healthcare providers do to get rid of back mice?

    There's no single treatment for back mice, as it's a catch-all term for any number of conditions with painful lumps on the back. That said, benign lumps that aren't causing pain or interfering with mobility can be left alone. Otherwise, injections of medication and/or steroids may be helpful. Surgery may be possible, as well.

  • When should a lipoma on the back be removed?

    Unless it's causing pain or making it difficult to move, there's no reason to remove a lipoma, as these growths are benign.

  • What can cause fat herniation on the back?

    One cause, known as subfascial fat herniation, occurs when fat protrudes through a tear or hole in the fascia in the low back.

  • Can back lipomas feel squishy?

    Not usually. They tend to be feel firm and rubbery and move beneath the skin when gently nudged.

  • What kind of healthcare provider should I see for an episacral lipoma?

    If you know for sure a lump on your back is an episacral lipoma, your general practitioner may send you to an orthopedist or orthopedic surgeon. You also may get pain relief from a massage therapist who's familiar with the condition.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Ries E. Episacraliliac lipoma. Am J Obstet Gynecol 1937; 34:490-494.

  2. Associated Bodywork and Massage Professionals. The problem with the back mouse.

  3. Bicket MC, Simmons C, Zheng Y. The best-laid plans of "back mice" and men: A case report and literature review of episacroiliac lipoma. Pain Physician. 2016 Mar;19(3):181-8.

  4. Rosati E, Mariani D. The role of episacroiliac lipomas as a cause of pseudolumbago-sciatica syndromes. Arch Putti Chir Organi Mov. 1990;38(2):339-347.

  5. American Academy of Orthopedic Surgeons: OrthoInfo. Lipoma. Updated August 2018.

  6. Tiegs-Heiden CA, Murthy NS, Glazebrook KN, et al. Subfascial fat herniation: sonographic features of back miceSkeletal Radiol. 2018;47(1):137-140. doi:10.1007/s00256-017-2772-9

  7. Erdem HR, Nacır B, Özeri Z, et al. Episakral lipoma: Bel ağrısının tedavi edilebilir bir nedeni [Episacral lipoma: a treatable cause of low back pain]Agri. 2013;25(2):83-86. doi:10.5505/agri.2013.63626

Additional Reading

By Anne Asher, CPT
Anne Asher, ACE-certified personal trainer, health coach, and orthopedic exercise specialist, is a back and neck pain expert.