Are Back Mice Real?

Back mice is a non-medical term used to describe painful masses of fat in and around the hips, the end of the spinal column (sacrum), and lower back. The term is used by some—chiropractors, in particular—to describe several different conditions.

Some professionals argue against calling such bumps "back mice" because the term is not specific. They argue that it may lead to misdiagnoses or incorrect treatment.

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

What Are Back Mice?

Back mice are painful, lumps of fat (lipomas) that protrude (herniate) through the lumbodorsal fascia. This is the network of connective tissue that covers the deep muscles of the low and middle back.

Back mice were first described in medical literature in 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:

• Iliac crest pain syndrome
• Multifidus triangle syndrome
• Lumbar fascial fat herniation
• Lumbosacral fat herniation

Back Mice Symptoms

Back mice lumps can often be seen under the skin. They are typically tender to touch and can make it hard to sit in a chair or lie on your back, since they often appear on the hip bones and sacroiliac region.

Back mice:

• Feel firm or rubbery
• Will move under your skin when poked
• Form unsightly lumps
• Cause excruciating pain

The pain associated with back mice results from pressure being placed on the lump, which compresses the nerves. Damage to the underlying fascia can also cause pain.

Diagnosis

Some people do not realize they have lumps until pressure is exerted on them. In fact, back mice are often found by chiropractors and massage therapists during routine treatments.

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

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

Differential Diagnosis

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, your healthcare provider may finalize diagnosis by ruling out other causes such as:

• 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.

Treatment of Back Mice

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

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

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.

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 fatty lumps under the skin that cause pain by compressing nerves and damaging your fascia. They move if you press on them and mostly show up in the lower back and hip area.

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