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What are Back Mice & How Can It Be Treated?

What are Back Mice?

Back mice is a nonmedical term used for painful lumps on the lower back or hip or near it. The term was originally used by Peter Curtis in 1993 to describe episacral lipoma but is now referred to as different conditions.

Back mice is a firm rubbery, mobile nodule, located in the sacroiliac, posterior superior iliac and lumbar paraspinal regions.(1)

What Conditions Are Referred To As Back Mice?

Back mice, is a non-medical term that can refer to many conditions that include:

  1. Episacral lipoma
  2. Lipoma
  3. Iliac crest pain syndrome
  4. Lumbar fascial fat herniation

Episacral lipoma

A small, tender, subcutaneous nodule present under the skin is known as episacral lipoma.

It occurs as the dorsal fat pad poles through a tear in the thoracodorsal fascia, a connective tissue that holds the back muscles in place.

They are primarily seen occurring in the posterior iliac crest that is the top outer edge of the pelvic muscle.


Abnormal overgrowth of fat cells that leads to the formation of lumps under the skin is known as a lipoma. They are considered non-cancerous tumors.

Iliac Crest Pain Syndrome

Also known as an iliolumbar syndrome, iliac crest pain syndrome is the result of a tear in the iliolumbar ligament.

The tear occurs as a result of repeated bending motion or twisted action of the iliolumbar ligament. It can also be due to falls, sports injuries, or a car accident.

Lumbar Fascial Fat Herniation

Lumbar fascial fat herniation is the protruding painful mass of fat through the lumbodorsal fascia (A thin, fibrous membrane that covers the back’s deep muscles).

Other conditions that can be called back mice are:

  • Sebaceous Cyst: A fluid-filled capsule that occurs between the epidermal and dermal layers of the skin. Just like lipoma, they are also benign.
  • Subcutaneous Abscess: It is a type of abscess in which pus collects under the skin. These are painful and in later stages get red, and inflamed.
  • Liposarcoma: These are the malignant tumors that occur as fatty growth inside the muscles.

Diagnosis of Back Mice

Back mice are often diagnosed by injecting local anesthesia into the lump. It is believed that if there is pain relief then the lump is a black mouse.(4)

How Are Back Mice Treated?

Unless there is unbearable pain, back mice do not require any treatment.

Treatment for back mice primarily consists of local anesthetic injections such as lidocaine and steroids. A study indicates the participants were quite satisfied with the treatment consisting of an injection of local anesthesia and corticosteroids.(2)

If surgery is indicated, it would involve the excision of the mouse and repair treatment of the fascia. It is the only method to achieve a long time relief from the pain.(3) There is complication involved with excisional surgery that includes scaring, bruising, uneven skin texture, and infection. A doctor should be consulted if there is a fever, increasing pain, bleeding, or discharge following the surgery.

Some people have hundreds of back mice and the removal of all of them becomes impossible. For smaller and extensive back mice, fluid liposuction may be explored.

Complementary and Alternative Treatments for Back Mice

Chiropractors believe that back mice can be treated by combining acupuncture and spinal manipulation. These are less invasive methods of treatment and do not cause any harm.

A study done in 2016 reported that injection of local anesthesia or steroid into the nodule followed by dry needling (a procedure in alternative therapy that is similar to acupuncture), improved pain relief.(4) The limitation of the study was that it was done only on one subject.

If having a painful lump on the lower back or hips, it is good to discuss the same with a doctor. He can diagnose the condition and recommend a suitable treatment plan.

Sheetal DeCaria, M.D.
Sheetal DeCaria, M.D.
Written, Edited or Reviewed By: Sheetal DeCaria, M.D. This article does not provide medical advice. See disclaimer
Last Modified On:February 27, 2021

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