1982 Ercegovac et al – Nodules in the sacroiliac region

This is a very interesting SERBIAN paper about the nodules in the sacroiliac region (also named back mice) from a doctor that discovered by exploring himself, first thinking that they were synovial cysts (he even presented it in a congress) and discovering later their “fatty nature” -he called them xanthoadipose nodules-.

He applied his own experience of pain improvement after local injection with anesthetic to treat 2,000 patients, according to him, with good outcome.

They presented the clinical significance and the treatment options of what they called the xanthoadipose nodules in the sacroiliac region.

They presented clinical, laboratory, surgical, histological, and thermographical tests. The authors are convinced that they have discovered a “new pathogenic mechanism of lumbar pain” and the method of its treatment. Surprisingly, the authors said that THEY DIDN’T FIND ANY OTHER STUDIES about these fatty nodules in the sacroiliac region (Personal notes: Obviously, they must refer to literature in their own language, because there were many previous articles, mainly from the 50’s, about back mice).

In their summary they state that they found that the painful nodules in the sacroiliac region are warmer than the contralateral symmetrical tissue (noticed by local palpation and by thermography). They said that the histological preparation have signs of autoimmune reaction.

The authors insist that the signs of inflammatory findings in the histological examinations are confirmed by the thermographic study. (Personal note: But they do not consider that maybe the increase in temperature is due to the heat production by the fatty tissue burning fat or by a vasomotor effect).

Neither they present any explanation why the anesthetic injection could be curative in an autoimmune inflammatory process.

They say that they have a LARGE study, but they do not present any statistical analysis. They state that they cured more than 2,000 patients from this lumbar syndrome.

Apparently, N. Ercegovac did not publish any further related study about this subject.

Personal notes about the original article:

[Xanthoadipose nodules in the sacroiliac region and their clinical importance lumbar and sciatic pain]

Ksantoadipozni cvorovi sakroilijacnog predela i njihov klinicki znacaj. Lumbalni i ishijalgicni bol.

Ercegovac, N.; Davidovic, R.; Tasic, M.; Bojanic, N.; Citic, R.; Milosevic, M.; Ledic, S.; Guduric, B.; Pervulov, V.

Vojnosanit Pregl; 39(3): 177-83, 1982 May-Jun.

Balgrade, Serbia

Ercegovac et al. introduction:

Lumbar and sciatic pain syndrome are very common painful phenomena, which can deprive one from their basic life daily activities.

The lumbar and sciatic pains have received much attention from various specialists, and several terms have been used to refer to them: sciatica, lumbosciatalgia, neuritis, lumbago, radicular ischemia, and acute lumbar syndrome. Anyway, these terms do not indicate the pathogenic factors that may be involved to the physician.

The pathogenic factors can include: mechanical compression, and traumatic, metabolic-endotoxic, exotoxical, vascular and psychogenic factors.

The works of Schmorla and Junnghansen (1932) and Mixtera and Barra (1934) assumed that the commonest etiology was the compression mechanical nature caused by changes in the lumbosacral part of the spinal column (protrusion and prolapse of the interverterbal disc, spondylosis, spondyloarthrosis or tumors). But Ercegovac et al. warn that other causes shouldn’t be neglected.

Ercegovac presents himself as his “first CASE”

In 1967 one of the authors, N. Ercegovac, during a period of intractable pains in the sacroiliac region by his own palpation, revealed 3 distinctly limited painful nodules in the area of the superior posterior iliac spine. Then, since the previous pain treatment was ineffective, he had the idea of infiltrating these painful nodules with a 1% solution of novocaine. The effect was spectacular pain disappearance immediately after infiltration, and during the day, there was a lessening of the intensity. During the next few days, infiltration was repeated, which led to a complete disappearance of pain.

Since this personal experience they began a study with around 1,000 patients. They estimated that these patients were mainly unsuccessfully treated under various diagnoses for a long time: lumbosciatalgia, disc hernia, spondylosis.

BUT WHAT WERE THE NODULES? At first, Erecgovac et al. thought it was a kind of synovial cyst… Later, they had a surprise.

At first, they thought that the nodules were “synovial cysts” or “bursa subcutanea” because they showed by palpation as completely restricted encapsulated bodies.

They attended the World Congress of Neurosurgeons in Tokyo in October 1973 under the title:

New Approach to the Problems of Ethiology, Conservative and Surgical Treatment of Painful Inflammatory Changes in Synovial Sacs of Sacroiliac Region (See references).

But they got a GREATEST surprise when they decided to remove one of the nodules for histological identification. They found that the nodules could range from grains of corn to plums and lie over the posterior iliac spine individually or in clusters.

The histological examination REVEALED the following features:

nodules in the sacroiliac region

-A structure that possesses a CONNECTIVE CAPSULE filled with xanthoadipocity tissue.

-Loose fat tissue (figure 2).

-And also cells with vacuolated cytoplasma (figure 3: Surface of the giant multicellular cells).

-Blood vessels present a thick caliber, indicating their high functional activity.

-An arteriolo-venous shunt Sucquet-Hoyerov channel (figure 4: arteriolo-venous shunt of glomerular type). With thick wall.

-Veins are sprinkled with small lymphoid cells of scar tissue and large hyperchromic nuclei (figure 5: wall veins and their perivascular structures). The presence of these nuclear elements in venous blood vessels indicates a local reaction.

Symptoms and diagnosis of the nodules in the sacroiliac region, radiation patterns and neuropathic presentation

 The leading symptom is pain in the lumbosacral region, often accompanied by the rigidity of the paravertebral musculature on the homolateral side. Depending on whether there are acute or chronic changes in the nodule, the pain can be sharp or dull.

The intensity of the pain can be so strong that the patient binds on the bed and prevents him from walking.

Pain can be localized only in a specific area above the posterior iliac spine, but it can also be lowered into the gluteal region and leg in the back of the thighs or even to foot with feeling of tingling in the toes.

Sometimes the pain develops toward the hip or the inguinal region, and even to the scrotum.

Intense presentations accompanied by abnormal “sweating” and painful paresthesia in the form of “ants”.

The patients usually describe the onset of pain in the lumbar or sacroiliac area, which gradually intensifies. Sometimes the onset occurs suddenly during a movement or in the course of physical activity. Then the pain is sharp and forces an antialgic attitude.

When changing the position of the body from lying to the standing position, the patient rolls or pulls to the edge of the bed, and then, supporting both hands on the edge of the bed, bends his legs and gradually rises.

Patients declare that they feel worst in the morning when they get up and they need a shorter time to walk around the room to flex, after which the pain becomes tolerant and the movement is easier.

Sometimes they describe a feeling of warmth or contrary cold in the lumbosacral and gluteal region.

Palpation in the painful nodules is a cardinal finding to the diagnosis.

The most painful spot is often localized in the area of superior of the posterior iliac spine or along the iliac crest.

In the clinical examination there can be pain when straightening the leg as in the sciatica.

The rise in temperature, a finding on palpation and on THERMOGRAPHY

There is usually a LOCALLY ELEVATED TEMPERATURE in the palpation of the painful nodule in relation to the symmetrical healthy side, which confirms that it’s of inflammatory nature.

nodules in the sacroiliac region

This elevated temperature was confirmed by thermographic inspection.

They found a rise in the skin temperature above the pain nodule compared to the other symmetrical side by 0.8-2.1ºC, which undoubtedly points top the pathological process (it is considered normal until up to a 0.5º C difference).

They performed the examinations in a room at 19º C after 10 minutes of cooling. They also investigated other signs of pelvic infection or neoplassic illnesses.

(Personal note: They assumed that the increase in temperature was pointing to an inflammatory process, they didn’t consider that fatty tissue can burn fat to produce heat or there can be a vasomotor reaction).

They didn’t find any sensitive or motor defects with neurological examination. Except for long-lasting pain patients, or patients that had the xanthoadypose nodules and a radicular compression syndrome at the same time. Also in patients that have been in bed for a long time, there was certain muscle hypotrophy.

Ercegovac et al. Conservative treatment: IMPLETOL injections and anti-inflammatory and muscular relaxants.

 IMPLETOL (procaine 2% + caffeine 0.25%).

nodules in the sacroiliac region

The treatment of lumbar or lumbosciatalgic pain syndrome of this origin is primarily conservative, and it has a good prognosis. The surgical removal is reserved to cases of shorter periods of painless intervals or allergic reaction to the application of anesthetic agents.

Initially, the nodules were injected with a solution of 1% novocaine. But later they used 5 ml of IMPLETOL Bayer Yugoslavia.

5-10 minutes after the first injection there usually was a SPECTACULAR improvement with a complete disappearance of the pain and relaxation of the paravertebral muscle spasm, or the intensity of the pain decreased in a very high percentage.

In easier cases, only 1-2 infiltrations were sufficient, while for a total cessation of severe cases, 5-10 infiltrations were usually sufficient given them on daily basis or every other day.

In this way they achieved painless intervals from one to several years. In addition to Impletol, they used oral anti-inflammatory painkillers such as Kofan, Dorsilon and Paraflex. They also treat with the B polivitaminic (B-1, B-6 and B-12).

Rehabilitation after the acute phase ensures faster recovery and faster return to work abilities.

The surgical treatment was reserved for the more frequent relapsing cases and was performed extremely rarely. Figure  shows the most commonly used operative cut.

nodules in the sacroiliac region

The removal can be done with local or general anesthesia. By using local anesthesia they noticed that the patient indicated sharper pain along the sciatic nerve while removing the nodule from its substrate. They closed the operative wound without drainage and they did not have any postoperative complications. In NONE of the cases they performed for several years there was recurrence of the pain.

nodules in the sacroiliac region

They used “rendgenska terapija” X-ray therapy with anti-inflammatory dosage to treat patients that could not be taken injection or given anti-inflammatory drugs. They used voltage 140KV, current 6mA, and filter 0.5 mm Cu and 30 cm distance with generally good results.


Their patients included people from both sexes from 20-70 years. The largest number belonged to ages between 25-50 years old. More frequently women than men.

It seemed to be more frequent with certain professions. Maybe related to microtraumas or often changes of temperature.

They also mention that the causative agent of the pain occurrence could be related to the course during or after viral infection. And it may also have a relation with certain pelvic infections.

They hypothesize about a biological function of these nodules, as being a kind of “strazari” or “guards”of the lumbar and sacral bones. They also noticed that they also seem to respond to all the inflammatory events in the pelvic organs.

Published in September 2018 By Marta Cañis Parera    ORCID iD icon


Ercegovac N, Davidović R, Tasić M, Bojanić N, Citić R, Milosević M, Ledić S, Gudurić B, Pervulov V. [Xanthoadipose nodules in the sacroiliac region and their clinical importance. Lumbar and sciatic pain]. Vojnosanit Pregl. 1982 May-Jun;39(3):177-83. Serbian. PubMed PMID: 6214075.