This is a quite simple and short article WRITTEN IN FRENCH by doctor Marcel Monnerot-Dumaine about Le lipome épi sacro-iliaque (also known as back mice) from 1955. It was published in the Revue médicale du Moyen-orient while he was working in Port Said, a city in Egypt.

The author is also known for the “Monnerot-Dumaine formula about ideal body weight” and many books about several subjects.

It is a short article with 2 mentions to personal cases. He thought that he had discovered a new nosological entity until he read André Sicard’s article about these painful lipomas.

He also says that “Le lipome épi sacro-iliaque” has synonyms as “Épi-sacro-iliac lipoma de Lewis” or “Nodule inflammatoire sacro-iliaque de Florentin et Louyot” (other names for back mice).

He writes in a very clear and easy narrative. His main message is to warn the doctors that the pathological findings in the examination of the spine sometimes can mask the painful nodules as a cause of the lumbosacralgia or lumbociatalgia syndrome.

He himself does not get deep on the underlying causes of “Le lipome èpi sacro-iliaque”, he mentions Copeman and Ackerman’s and Florentin and Louyot’s theories.

Monnerot-Dumaine summarizes that “Le lipome épi sacro-iliaque” (back mice) is a perceptible fatty nodule beneath the integuments that cover the superior part of the sacroiliac articulation. It is especially observed, but not exclusively, in obese women.

Most often it is painless, but sometimes it is the seat of a local pain and irradiation, causing lumbosacraligia, and even sciatic pain. Novocaine injection often heals it. And some other times, excision is necessary. It can coexist with other vertebral abnormalities, discitis, sacralization, and sacroiliac lesions that may be a mask factor to recognize “Le lipome épi sacro-iliaque”.

The relation between the spine lesions and the lipoma is difficult to explain.

Notes on the article:

Le Lipome épi sacro-iliaque

Par M. Monnerot-Dumaine (Port-Saïd)

For the last 4 years, the author observed a NODULE situated in front of the sacroiliac joint in some women with lumbar pain, and he was struck by the fact that the NOVOCAINE infiltration of the nodule often cured the LUMBAGO.

He thought he was holding a new nosological entity, and then he read the paper of his colleague André Sicard: Lipomas epi sacro-iliac and lumbociatic. He found the same that Sicard observed except the fact that novocaine cured them and not always surgery was necessary.

Sicard, being an excellent NEUROSURGEON, healed his patients by removal of the nodule. Then there was an OPEN LETTER from M. Bonduelle and Sallou that pointed out the effective treatment by infiltration.

So what is the nodule he called ”Le lipome épi sacro-iliaque”? The author mentions Copeman and Ackerman’s and Florentin and Louyot’s work.

The histology is very simple, they are FAT CELLS. They are not much different from painless lipomas. The difference is that they can present an edematous process or a herniation (Copeman and Pugh) or they can be the reminiscence of the Aschoff nodules of young people (according to Florentin and Louyot). Exceptionally, a small necrotic foci with inflammatory process has been observed.

The compression or irritation of the intralipomatose nerve cells by odematose adipose cells in their capsule could explain the pathological symptoms according to Copeman and Ackerman. It could also have an endocrine origin (Florentin and Louyot).

Two cases of “Le lipome èpi-sacro-iliaque” from Monnerot-Dumaine

It usually happens with obese woman, but not always. The PAINLESS NODULE can be a fortuitous discovery, because MOST NODULES are not painful. BUT it can cause lumbalgia, the pain can radiate far from the nodule. It can radiate to the leg (less the foot), usually posterolateral (rarely anterior to thigh).

Usually the patient is not aware that the lipoma is the cause of pain.

The pain has no particular characters; it is continuous, with little or no rest, and it is not variable with the positions, except flexion. Sometimes it causes contracture of the muscles of the region. It can be considered a lumbosacralgia or lumbo-sciatalgia.

On palpation, there is the finding of a round/oval mass as big as a pea or “nolsette” on the posterior side of the sacro-iliac joint, at the level of the lateral fossa of the sacro-iliac joint. The nodule can be unique, or in number 2 or 3 about 5-6 cm from the midline.

The affection can be acute or chronic. It may go forever or may be recurrent.

In general, there are not findings in the vertebral exams. But sometimes there can be radiological findings such as discites or sacralization.

The nodule named “Le lipome épi sacro-iliaque” made fun of the author

“J’ai eu l’occasion d’observer de tels cas. J’ai cherché midi à 14 heures, soigné des vertèbres, alors qu’un nodule se moquait de moi à la portée de ma main.”(The author was searching vertebrae causes while the nodule made fun of him) by Monnerot-Dumaine.

He presents the case of a woman who had everything in her vertebrae to justify low back pain: pinched intevertebral space, lumbar scoliosis, osteophytes…and that after infiltrations, rest analgesics NOTHING HELPED. Before considering even an intervention of the disc, THE AUTHOR DISCOVERED a LARGE PAINFUL NODULE. When they infiltrated the nodule, the woman got free of pain.

Another patient was sent to the author that was laminectomized maybe to have reintervention, before anything else and after the experience with the woman, he didn’t miss the nodule again so he explored him and find out a nodule. After infiltration, he improved.

Boundelle and Sallou even say that the association of the lipomas with underlying vertebral lesions as disc lesion is so frequent that maybe the lipoma is a symptom of underlying vertebral disc lesion.

Treatment of “Le lipome épi sacro-iliaque” by Dr. Monnerot-Dumaine

The author emphasizes the importance that this insignificant nodule can have. They recommend that the novocaine infiltration could always be a help to do a diagnosis. Novocaine infiltration makes the pain disappear, and then the patient and the doctor can be sure that this was the cause of pain. They infiltrate intra and perinodular; it rarely needs to be repeated more than 3 times. Not just it cures the lumbago, but also the nodule sometimes disappears. There can be some rebel cases where the pain doesn’t disappear and maybe the cause is other than the nodule.

Published in July 2018 By Marta Cañis Parera   

References:

• MONNEROT-DUMAINE M. [Episacroiliac lipoma; synonyms: episacroiliac lipoma of Lewis, Florentin and Louyot’s inflammatory sacroiliac nodule]. Rev Med Moyen Orient. 1955 Apr-Jun;12(2):191-4. French. PubMed PMID: 13255468.
• SICARD A, LORD G. [Episacroiliac lipomas and lumbo-sciatica]. Presse Med. 1952 Jul 26;60(50):1073-4. Undetermined Language. PubMed PMID: 13026891.
• FLORENTIN P, LOUYOT P. [Inflammatory nodes of the sacro-iliac region]. Rev Rhum Mal Osteoartic. 1952 Mar;19(3):255-9. Undetermined Language. PubMed PMID: 14958324.
• COPEMAN2 WS, ACKERMAN WL. Fatty herniation in low back pain. Lancet. 1947 Aug 2;2(6466):188. PubMed PMID: 20255787.