This is a short article about the sacroiliac lipoma (also known as back mouse or mice) from 1961 by two authors George F. Wollgast and Charles E. Afeman from Denver.
Sacroiliac (Episacral) Lipomas
George F. Wollgast MD and Charles E. Afeman MD
Department of surgery, St Luke’s Hospital, Denver
The authors refer to the work of Copeman, Herz, Sicard and Schmidt-Voigt.
Wollgast and Afeman start the article about the sacroiliac lipoma by saying:
“Lipomas in the sacroiliac area are a FREQUENT cause of pain in the lower back and lower extremity. They are SELDOM considered in the differential diagnosis of back pain”.
They are surprised that there are not many articles since 1950
They mention that they are unable to FIND references of the condition in the American literature since 1950; several recent reports are found just in foreign literature.
Schmidt-Voigt reported 153 cases of sacral pain, 72 belonging to the lipomatous category. (Ages from 17-75, 57 females).
Sicard and Lord also emphasized that these nodules are responsible for certain lumbosacralgias and that they produce sciatic pain.
Copeman published a large anatomical report in 1944.
Clinical picture of these lipomas
-The authors agree that the location of pain is often ill defined, variable and affected by position.
-Pain can vary in intensity, duration, intermittence, and can be recurrent or constant.
-Pain may be severe and disabling but it is usually of a nagging, annoying type.
-Pain often radiates to the buttock and thigh, but seldom crosses the knee and never involves the foot.
Diagnostic clues
-The lipomatous syndrome can be suspected by careful palpation of the low back that reveals a tender nodule.
-The location is not constant, but usually over the sacroiliac area.
-The pressure over the nodule causes the patient to wince and usually to state “that is it”.
- The local anesthetic of the painful lump helps diagnose and gives relief.
- Surgery is advised if the relief obtained is not permanent.
- Voigt’s patients were PERMANENTLY relieved by 4-6 injections of local anesthetic agent into and around the tumor over a 2-week period.
Voigt states:
“If temporary relief is not obtained after 1 or 2 injections then the diagnosis of the lipomatous syndrome should be considered doubtful”.
Surgery technique
-With local anesthesia a TRANSVERSE incision is made over the tender tumor.
-On incision of the superficial fascia the ENCAPSULATED FAT MASS is seen.
-It is mobilized; the pedicle is ligated and then removed.
-The wound is closed over a small drain.
Surgery results
They operated on many cases during 25 years with rare failures.
They present 4 illustrative cases
Case 1
A 34-year-old man. Recurrent low back pain radiating to the right lower extremity for 6 years. The present episode was for 3 months. The only finding was a tender nodule over the right sacroiliac joint. Pressure accentuated the pain and produced radiation into the right thigh.
Procaine 1% afforded complete temporary relief. He was operated on later with a pathological finding being: lipoma 5.5x4x2.2.
Case 2
A 35-year-old man. Pain in right hip radiating down his right thigh to the lateral surface of the leg for 3 months. The pain was relieved by sitting and was not increased by straining.
Palpation revealed a small nodule in the region of the right sacroiliac joint (a sacroiliac lipoma). Pressure produced pain and radiation into the right thigh. Infiltration of anesthetic produced temporary relief. He went under surgery excision with good result. Pathological findings said: “lipoma sections with adult fat showing various degrees of fibrosis”. Fat cells tend to revert to connective tissue. Surrounded by a fibrous reticulum.
Case 3
A 48-year-old female. Presented disabling pain to lower back and right thigh for 6 weeks. A tender nodule (or sacroiliac lipoma) was found and excised with good outcome.
Case 4
A 72-year-old female. Low back pain for 3 weeks that radiates to left thigh and leg. Examination showed an EXTREMELY tender nodule overlying the left sacroiliac joint (a sacroiliac lipoma). Pressure on nodule provoked electric-shock-like pain into the left lower extremity.
Procaine 1% infiltration afforded relief for 6 hours. The surgery gave immediate relief.
Published in June 2018 By Marta Cañis Parera 
