1942 Macdermot

MacDermot called the intriguing painful nodules: sacro-iliac lipomata (another name for back mice).

This is an excellent article from Dr. MacDermot that warns the medical community that there are at least 3 pain syndromes related to the sacro-iliac lipomata: low back pain, leg pain and low quadrant abdominal pain.

Dr. MacDermot got intrigued to study the sacro-iliac lipomata (back mice) after a visit from Dr. Ries from Chicago.

Dr. MacDermot expresses a lot of humanity and warns the medical community that the lack of knowledge of this entity sometimes mean that these type of patients receive very little sympathy from the doctors, and that they are usually put into the neurotic wastebasket.

 NOTES about the article:

 Sacro-iliac Lipomata. 


Bulletin of the Vancouver Medical Association,18: 185,1942.

Dr. J. H. MacDermot from Vancouver presented this work before the Vancouver Medical Association, Feb 3, 1942.

sacro-iliac lipomata

It started saying that:

“of all the problems with which we medical men have to deal, the most pressing of solution, and often the most difficult, is that pain”.

sacro-iliac lipomata

About the sacro-iliac nodules he said:

“The more often you think of them, and look for them, the more often you will find them”.

“You will be able to help quite a few people to keep out of the bin labelled neurotic, and will make it unnecessary for them to go, as a last resort in their real distress and misery, to quacks and irregulars”.

He states that there are still a lot of acute and chronic pains that are of unknown cause, so anyone who can help to unravel the problem of some of them is something of a benefactor to mankind. He hopes that the paper he is presenting that night would be of value to some of the listeners, some others already know from him about it.

It all started with the visit of Dr. Ries from Chicago how was very enthusiastic about sacro-iliac lipomata

sacro-iliac lipomata
It all started with the visit of Dr. Emil Ries from Chicago.

Some years ago, Dr. Emil Ries, from Chicago, visited Vancouver to give a lecture to the Vancouver Medical Association. Dr. Ries passed away since then. He was a very eminent American surgeon of the Chicago Postgraduate Hospital. He wrote a paper in 1937 entitled Epi-sacro-Iliac Lipomata.

Ries explained the case of a woman with chronic backache for years that had suffered more than got benefits from the doctors (she got some teeth, and certain organs removed, had belts and orthopaedic supports) and the pain still persisted. MacDermot comments that this was a “typical story” in the condition of which he was speaking that night.

Dr. Ries did what nobody did before: exploring inch by inch

sacro-iliac lipomata
Dr. Emil Ries explored woman’s back inch by inch, and found a small nodule that elicited sever pain.

Dr. Ries explored that woman, and “proceeded to do what nobody had really done before“. He went over the back inch by inch, and found, near the sacro-iliac joint on one side, a small, elastic, rubbery little mass, very tender, freely moveable. Manipulation of this small tumour and pressure elicited severe pain, which was, according to the patient, the same kind of pain as that from which she had suffered for so long. He removed the tumour, and the patient obtained complete relief. Pain didn’t return. On examination, he found that the nature of tumour was of lipoma, but with NERVE FIBRILS.

Dr. Ries gets excited and examines 1000 patients in Chicago

Dr. Ries got excited about this case and explored randomly 1,000 patients in the city of Chicago. He found that 1/3 of the explored had these nodules in the vicinity of the sacro-iliac joint. About them 1/3 more had backaches or other pain sometimes elicited by pressure on tumour.

Dr. Ries improved his technique

Dr. Ries first injected 2% novocaine. If this gave a definite relief, he felt that this was a proof of the casual relationship between the tumour and the pain. If the pain remained away, as he found in some cases, he did nothing further. If pain returned, he operated to remove the lump.

The positivism of Dr. Ries in Vancouver

Dr. Ries was so positive of “the reality of these tumours as a frequent cause of backache” that, during his visit, he offered to study all the cases of backache of the hospital that had not yielded to treatment. He stated that a large percentage of them would show these lipomata. He did, as a matter of fact, find quite a few, and demonstrated them during and after his lecture.

 Dr. MacDermot goes further, he found 3 syndromes related to sacro-iliac lipomata

sacro-iliac lipomata
Dr. MacDermot found 3 syndromes related to the back nodules. Back pain, Pain related to the leg/s and lower quadrant pain of abdomen.

After Dr. Ries’ visit, Dr MacDermot started to look for these lipomata, and found that those findings by Dr. Ries were only part of the whole picture. Ries only described backaches; MacDermot found at the moment 3 DISTINCT SYNDROMES, which could be caused by these lipomata.

He noticed that in fact they are not really lipomata, but more like a “bulk of the fat tissue”, and the presence of nerve fibrils suggested these may be “neurolipomata”.

About the name: MacDermot noticed that “epi” means upon, and the tumours are more “para” alongside the sacro-iliac joint. That’s why he uses only the term sacro-iliac nodules.

MacDermot’s FIRST SYNDROME: Back pain due to sacro-iliac lipomata

Pain is often severe, disabling at times. Generally lasting for a long time. It is not aggravated by work, often comes while sitting or turning over bed. No relation with menstrual period. Not relieved by defecation or passing of gas, not connected with micturition. Salicylates have no effect, and sedatives are of little use. Examination of feet and rectum shows nothing. X-rays negative. Postural or occupational causes ruled out. The only finding is the “lipomatous nodule”, in the sacro-iliac region, tender, which “slips under your finger”, gives pain on pressure and the removal or injection (anaesthetic) will cause the pain to vanish immediately.

MacDermot’s SECOND SYNDROME: Pain radiated to the leg/s due to sacro-iliac lipomata

The radiation of pain down one leg or sometimes both characterizes this pain. There may or not be backache as well. Pain doesn’t usually go further than the knee, but occasionally as far as the ankle. Frequently, pain runs down the front of thigh, along genitocrural distribution. The pain is frequently crippling and will cause limping. It is erratic in its appearances, can go away completely and come back again another day. These cases are often diagnosed as sciatica by mistake. In these cases there is no atrophy; however, there is tingling and tenderness. The pain usually stops at the knee, suggesting pressure on the “obturator nerve”. Radiation down the front thigh is against sciatica. MacDermot states that “diagnosis of sciatica” should be made if signs are unmistakable or if the pain is not caused by sacro-iliac nodules.

MacDermot’s THIRD SYNDROME: Lower quadrant pain due to sacro-iliac lipomata (NOT gynaecological).

For him, the most interesting syndrome, since he saw rather dramatic cases. It is the least common. It should be of special interest in those who deal with gynaecological disorders (despite there are also cases in men).

Lower quadrant abdominal pain is one of the most difficult diagnostics, especially when it is vague, difficult to localise, without clear cause and resists all measures of relief. Especially, the pelvic organs of women, are often suspected as the “fons et origo mali”. These pains have been usually blamed to the uterus and ovaries, but Dr. MacDermot thinks that the pains are sometimes originated in the sacro-iliac region. Especially when there isn’t any real pelvic pathology, and there is a chronic intractable pain, sometimes disabling and crippling, sometimes associated with backache, not influenced by menstruation, not relieved by rest and without abdominal tenderness. Exploring the sacro-iliac region carefully can elicit a tender nodule that, on pressure, elicits the pain complaint. Injection with novocaine will settle the diagnosis. Therefore, the pain is not intra-pelvic but a referred nerve pain from branches that run around the patient.

MacDermot states three differences with Ries

First difference: Ries said that the nodules are always superficial, freely moveable, and easy to grasp between the fingers. But MacDermot sometimes finds also deeper ones, sometimes just too difficult to palpate. Then, he searches the tender spot, and finds the point of maximum tenderness with the point of the needle.

Second difference: Ries finds that “surgical removal with local anaesthetic” is the only needed thing. But MacDermot sometimes had cases that had to go all the way to the periosteum to search for the offending nodule; he sometimes had to use general anaesthesia.

Third difference: Ries said that pressure on nodule always reproduced the patient’s complaint, MacDermot said that it isn’t always the case. Nevertheless, anaesthetic injection can help absolve the area of guilt.

Considerations of MacDermot related to taken patient’s history:

sacro-iliac lipomata
The patients with the nodules recieved ver little sympathy from the doctors, and they are usually put into the neurotic wastebasket.

-His patients usually presented a long history of backache. Radiologists, orthopaedics and urologists had previously examined the patients without finding a real pain cause. By that time, it was common to remove one or more foci of infection (the teeth, tonsils, gallbladder). X-rays had been taken and proven negative. Belts and exercise prescribed.

-Very suggestive of this condition is that there is a long history of vague and unlocalised pain, the patient had taken many measures of diagnosis and treatment and the disability continues.

-These “type of patients” usually receive very little sympathy from the doctors, and they are usually put into the neurotic wastebasket. MacDermot says that before a diagnosis of neurosis, this entity should be discharged.

He says that sometimes doctors use the “word of neurosis” as a confession on the failure of the diagnosis.

Two considerations of MacDermot related to diagnosis:

sacro-iliac lipomata
MacDermot’s examine technique to find the back nodules.

Finding sacro-iliac nodules: One or more nodules can be found in neighbourhood of sacro-iliac joint. Varying on size from a split pea to a decent-sized bean. Firm pressure on these nodules causes pains that makes patient wince and elicits “patient’s previous complaint”. The nodule is firm, elastic, and slips under the fingers. It is easy to examine the patient sitting up, feet over side of examining table, back easily rounded, and patient relaxed. Sometimes one cannot find the nodule, but the tender spot can be found (injection of anaesthetic will help to determine if the nodule is the source of pain). Maybe the condition is due down to the periosteum without clear nodule (injection can sometimes give permanent relief, nevertheless).

Injecting novocaine 2%: Better to hold the lump anchored between the thumb and the forefinger of the left hand, then plunge the hypodermic needle into it, and inject novocaine. Massage the part gently, wait a minute, and then ask the patient to get down and move. The patient is very often surprised and says: “pain is much better”, or “completely gone”. If the patient does not have immediate relief, ask the patient to report next day, sometimes there will be less pain than usual. Pain relief can last hours or a long time. Surgical removal is the final option, and always after a positive injection managing. MacDermot says that the relief is often spectacular and that he doubts it could be just suggestion, since the past history of failed treatments made them not very “suggestible patients”.

MacDermot’s considerations with de differential diagnosis of sacro-iliac lipomata:

MacDermot advises not to be over-enthusiastic about this diagnostic. He calculates that about 10% of the population could have disability or discomfort from them. There are many other causes to be considered of back pain, so the best thing is to get into the habit of examining this area as a routine.

MacDermot’s considerations about sex incidence:

From MacDermot’s personal experience, he saw more cases in women than in men. But he argues it can be a result of several factors. For example, men’s backaches are much more ascribed to strain, occupation and injury and, therefore, miss the diagnosis.

MacDermot: What is the cause of pain of these sacro-iliac lipomata?

The author says clearly “I DO NOT KNOW why so much pain should arise from the presence of these small tumours”. They are mostly freely moveable and many people have them without any pain. The microscopic examination shows nerve fibres among the fat cells, they conclude it must be of the nature of neuro-lipomata. The fact that much relief can be obtained by injecting them also suggests that there must also be a connection with pain centres themselves. The fact that relief is obtained by fasciotomy suggests that there must be pressure or tension involved.

The size of the nodule is not proportional to the pain it can cause. MacDermot noticed that even an insignificant little lump could give much pain, so “appearances are NOT TO BE TRUSTED”.

MacDermot’s treatment options of sacr-iliac lipomata

Removal gives the most permanent results but it is not always necessary. The preliminary injection is often enough, and two or three repetitions will give the desired result. If not, then removal should be done. MacDermot advises that in certain cases “the most trouble ones” sometimes are by the periosteum. He uses 2% solution of novocaine, also 1% solution gives excellent results, and large amount 50cc can be used at a time.

Some cases reports about sacro-iliac lipomata 1st syndrome: Backache

CASE 1. Unmarried woman 16 or 17 yrs. Thin, but quite healthy. She complained bitterly of attacks of severe backache, coming at intervals for years. She gave a vague story of previous injury due to a fall. She had been examined and treated by doctors, even by Dr. MacDermot, who gave her placebos which had done her no more good or harm than other previous treatments. After Ries‘s lecture, she came to MacDermot in despair, declaring she could not stand this pain any longer. MacDermot found very painful nodules in both sacro-iliac areas, pressure elicited very severe pain. He injected her with novocaine. The relief was immediate and very startling. After removal, she was free from pain.

CASE 2. Man aged 32yrs. Dr. MacDermot mentioned this case despite not having much information because it is one of the few men’s cases. Long-standing pain improved after nodules removed.

CASE 3. Woman telephone operator. Past history of many years of pain. She had tender nodules that were removed with some bleeding problems.

CASE 4. Widow woman of 52yrs. She had attacks of very crippling pain that made walking so painful and practically impossible. The pain is one-sided and extended into groin. She had a very painful nodule on the left side. After success, the doctor injection planned a removal with local injection that did not work well. The pain returned as bad as ever. He injected her every week with 2 or 3 cc of 2% novocaine, which made her very jittery. Then he changed to 1/2 of 1% novocaine diluted in 25-30 cc at a time, with no discomfort, and eventually good results, after 2-3 of these injections pain disappeared for good. From this case, the author learned that for many injections weak solutions in large amounts are better.

Some cases reports about sacro-iliac lipomata 2nd syndrome: Pain down the legs

CASE 1. Woman, dressmaker of 22 yrs. Married. Childless. She complained of severe periodic attacks of pain of left leg down to the heel, making her limp very badly. She has been carefully examined in New York. Salicylates gave no relief. Examination of back showed nodules on both sides. Injection of nodules of left side gave her relief. Three days after removal, pain returned less severely. Examining the wound, it showed considerable serum pent up in it. Letting serum out gave definite relief. Afterwards, the nodules of right side were also removed. This case showed the entity likeness to sciatica, but it is obviously not sciatica. It also showed that the serum as the nodule can produce pain by pressure on nerves.

CASE 2. Woman, 35yrs, unmarried telephone operator. Thin, but healthy. No history of trauma. Pain extended to ankle, worst in thigh, front as well as back. This patient was managed with injections of weaker solution of novocaine.

CASE 3. Woman 41 yrs, stout, sedentary. He mentioned it as an unsatisfactory case. The nodules were found, first injection worked, but later ones did not, and the woman discontinued the treatment.

Some cases reports about sacro-iliac lipomata 3rd syndrome: Iliac and abdominal pain with or without backache.

CASE 1. Woman 35yrs, multipara. The pain on left side of abdomen started on her just after an ectopic pregnancy. The pain was severe interfering with her work and sleep, making her miserable. They examine her and they could not find the reason of this obscure pain, she was the picture of misery. Despite MacDermot believed the pain was genuine and severe, the patient could be found unfortunately in the category of neurotic. MacDermot out of the despair of the patient explores the sacro-iliac regions, though it seemed to him to be “A PURE SHOT IN THE DARK”. He found very tender nodules over the left side. Very sceptically, he injected them, she obtained immediate relief; after that, she was a happy woman and didn’t need any other injection. MacDermot confessed about this woman’s case that to have given this poor woman relief after some three years of misery is one of the greatest pleasures that has happened to me in practice”.

CASE 2. WOMAN 49yrs, multipara. The patient complained of constant pain in the left lower quadrant. She had a terror of cancer. She suffered a rectal ulcer that was resolved, but the pain persisted. Then, MacDermot finds tender nodules on the sacro-iliac region. After injection, patient gets better; after two injections ,more pain was gone.

CASE 3. Woman 30yrs, housewife. Constant attacks of left lower quadrant pain. The pain was relieved after removal of nodules.

MacDermot’s final advice about the sacro-iliac lipomata

Dr MacDermot’s final advice is to always examine the backs for these nodules as a routine on this kind of patients with chronic recurring obscure pains and always, of course, exclude all other possible causes of pain.

It says “You will be able to help quite a few people to keep out of the bin labelled neurotic, and will make it unnecessary for them to go, as a last resort in their real distress and misery, to quacks and irregulars”.

“The more often you think of them, and look for them, the more often you will find them”.

Published March 2018 byBy Marta Cañis Parera   ORCID iD icon



  • MacDermot, J. H. Sacro-iliac Lipomata. Bulletin of the Vancouver Medical Association, 18: 185, 1942.

  • Ries E. Episacroiliac lipomaAm J Obstet Gynecol 1937;34:492-8