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Lower back pain is one of the most common complaints in human medicine. This pain is usually caused by lumbar strain, nerve compression, lumbar spine deformities, arthritis, and many other conditions related to musculoskeletal disorders. However, there are some interesting cases of lower back pain where patients also notice one or more lumps beneath the skin of the lower back region. If you have these or similar symptoms, you may have a condition also fibro-fatty nodules, fibroadenomatous nodules, episacroiliac lipoma, popularly known as "back mice".

What is "Back Mice"?

This condition is caused by damaged thoracodorsal fascia (layer of fibrous tissue covering back muscles). The protrusions of fat tissue through the damaged fascia are manifested as "back mice". They usually look like one or more small, movable lumps beneath the skin. They are sometimes asymptomatic, but they can also cause pain that is very similar to the common lower back pain caused by lumbar spinal nerve compression. Researchers have shown that not enough attention has been paid to this cause of lower back pain, despite the fact that both diagnosis and treatment are easy. A few studies were conducted to investigate the relation between lower back pain and "back mice", and they have all confirmed a positive association.


Patients with this condition are often given analgesics (pain relievers) with little or no success, and they are subjected to a series of unnecessary investigations performed by radiologists, orthopedists, and neurosurgeons that usually end up with no good answer to the patients' complaints. Ironically, the diagnosis is actually very easy to make. After locating the nodules, a small amount of local anesthesia is injected subcutaneously around them and if the pain alleviates or disappears, the diagnosis is confirmed. Your doctor may also order a biopsy of the lump in order to examine its microscopic features.


Surgical removal of the problematic nodules permanently removes the pain.

Local injections of an anesthetic and corticosteroid can sometimes offer prolonged pain relief as well, so this treatment can be used while waiting for surgery.

If you notice small hard lumps beneath the skin in your lumbar or sacral area and have associated back pain, please call on your doctor. The pain usually gets worse when you touch those lumps, and it also becomes worse during movements. This condition can be very disturbing and even cause disability, although it is benign and completely treatable. Therefore, it is important to visit a surgeon and point out the complaints you have.

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