Fibrous Tumors of the Omentum
FRANK W. NORMAN, M.D., Santa Rosa
FIBROUS TUMORS of the omentum are not often
diagnosed preoperatively. They may be noted at
exploratory laparotomy but usually only inciden-
tally unless they are part of an adhesive band pro-
ducing bowel obstruction or their pedicles become
twisted and cause infarction and abdominal pain.
Although not rare, such tumors are considered un-
common enough to warrant this report.
REPORT OF A CASE
A 48-year-old white stenographer sought medical
advice because of constant low abdominal distress
of 24 hours' duration. She had had no previous pain
of this type. Her bowel habits were entirely normal
and she had very little gas, bloating or indigestion
before the onset of the constant low abdominal pain.
There was no dysuria, urinary frequency, nausea
The patient had had appendectomy, cesarean sec-
tion and removal of a fibroid tumor from the uterus
eight years previously, subtotal hysterectomy six
years previously and bilateral vein stripping and
ligations five years previously. There had been no
vaginal bleeding since the hysterectomy.
The patient's mother had died of carcinoma of the
intestine, an aunt of heart disease, and her father
had peptic ulcer.
The temperature was 1010 F, respirations 20 per
minute, the pulse rate 88 and blood pressure 130/82
mm of mercury.
No organs or masses were palpable in the abdo-
men. There were several vertical operative scars in
the low midline. Pronounced tenderness was noted
over the entire lower abdomen, with rebound and
percussion tenderness especially under the surgical
scars. Peristalsis was normal and active.
On pelvic examination, the cervical stump ap-
peared to be slightly cyanotic and deviated to the
right. Bimanual pressure revealed a firm cystic
mass, well fixed, occupying most of the left ade-
Submitted Februy 12. 1963.
nexal area but extending slightly to the right of the
midline and displacing the cervical stump. The mass
was extremely tender on movement and could be
felt bimanually through the abdominal wall when
it was located with the pelvic examining finger.
On rectal examination the mass was noted to pro-
trude posteriorward into the cul-de-sac, compressing
the rectum. Proctoscopic examination to a level 15
cm above the anus was done with ease and old
brown feces were observed. The rectal mucosa ap-
peared normal. A guaiac test on a fecal specimen
was negative for blood.
As the pelvic mass was thought to be probably a
twisted ovarian cyst, exploratory laparotomy and
removal of the mass were recommended. The pa-
tient was put in hospital.
Leukocytes numbered 12,200 per cu mm with the
cell differential within normal range. The hemato-
crit was 46 per cent and the corrected sedimenta-
tion rate (Wintrobe) was 38 mm in one hour. No
abnormality was noted on urinalysis. On x-ray ex-
amination of the abdomen a slightly increased soft
tissue density in the left pelvic area, compatible
with a pelvic mass, was observed.
The abdomen was opened through incision at the
midline where there was considerable scar tissue
from previous operations. There was a small amount
of serous fluid in the peritoneal cavity. The omen-
tum was adhered to the anterior peritoneal wall.
No abnormalities were noted on palpation of the
abdominal organs. Five irregularly shaped ivory-
like tumors about 2 cm in diameter dangled from
the edge of the omentum on stalks from 1 to 2 cm
long. They looked somewhat like the small tassels
seen around the edge of a Mexican hat. The pelvis
was then inspected and a dusky purplish mass was
seen in the cul-de-sac. It was attached by thin and
fibrinous adhesions to the salpinx, the ovaries and
the small bowel. This incarcerated mass was at-
tached to the omentum by a pedicle which had been
twisted approximately eight times. The pedicle
joined the edge of the omentum near one of the
smaller masses (see Figure 1). The stalk was tran-
sected and the tumor was carefully dissected from
the surrounding tissues. It was then apparent that
VOL. 99. NO. 6
Figure 1.-A drawing showing the findings at laparotomy. Note the five ivory-like tumors hanging from the edge
of the omentum, and the incarcerated large fibrous tumor on twisted pedicle adhered in the cul-de-sac.
it was a tumor of the omentum on a long pedicle
which had become twisted and infarcted and had
become adherent in the cul-de-sac. There were no
lymph nodes present and all of the lesions inspected
appeared grossly to be benign. All the tumors were
removed and the pedicles ligated. When the large
tumor, which was approximately 10 cm in diameter
and well encapsulated, was cut open, it was ob-
served to contain several loculated fluid spaces with
degenerated fibrous tissue centers. The small tumors
were transected and found to be somewhat gritty
and fibrous. The abdomen was then closed and the
patient recovered rapidly and remained well.
The pathologist reported:
The large tumor was a previously opened, dark
brown nodular mass 9 centimeters in diameter
which had a smooth surface. The cut surface showed
what appeared to be a multilocular cyst space with
a firm, gray area of tissue, 3.5 cm in diameter, cen-
trally placed. Attached to one aspect of this nodule
was a tail of tissue 6 cm long and varying in diam-
eter from 1 to 0.4 cm and showing many twists.
Also examined were five nodules of gray-white tis.
sue with smooth surfaces, varying in diameter from
2.5 to 1.5 cm. Cut surfaces of these specimens were
gray and slightly bulging. Microscopic examination
of the sections from the multilocular portion of the
large specimen showed hyalin degeneration and
focal areas of hemorrhage throughout. The tumor
appeared to be principally fibrous and not a tumor
of adipose tissue. Tissue from the smaller specimens
was of fibrous nature, the tumors being typical
fibromas with interwoven bundles of fibrous tissue
in which there were some vascular channels (See
Figure 2). No abnormal proliferation was observed.
From the clinical description the origin of these
tumors would appear to be the omentum.
The pathologic diagnosis was: Fibrous tumors
from omentum with extensive degeneration in the
Embryologically the omentum is composed of
mesenchymal elements on its serosal surfaces, and
sandwiched between these are blood vessels, nerves,
lymphatic channels and fatty and connective tissues.
Theoretically, then, abnormal growths of this organ
could arise in any one or in combinations of these
one of the fibrous tumors showing
Figure 2.-Left, photomicrograph ofa typical section through
ight, interwoven bundles of fibrocytes (X450).~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
structures. Such, it would seem, is the case as evi-
denced by published reports of neurofibromas,
fibromas, lymphangiomas, liposarcomas and an-
giomas originating in the omentum.
The very nature of the omentum makes it sus-
ceptible to trauma, infarction4 and torsion3 of its
part and the literature contains many such reports.
Tumors of the omentum are more frequently re-
ported in foreign than in English-language litera-
ture. Malignant tumors originating in the omentum
Smith" reported a case very similar to the one
herein described and in a review of the literature
noted how few reports there were of fibrous tumors
of the omentum. Castleman,2 presenting a case of
neurofibroma. of the greater omentum accompanied
by diabetes mellitus, pointed out that certain tumors
of this nature produce an insulin-like protein which
may lower blood sugar levels.
In 1954 Ackerman'
classified benign tumors
of the omentum as: (1) Fibrous-local or diffuse,
and (2) Papillary-local or diffuse. He noted that
in a total of 56 cases of benign peritoneal and
pleural tumors reported in the previous 32 years,
only two were fibrous and these involved the pleura
Robb' reported a case of liposarcoma of the
greater omentum and discussed the rarity of malig-
nant tumors of fatty tissue in this area. In 1934
Ransom and Samson4 reviewed 75 cases of primary
tumors of the greater omentum and classified pre-
senting signs and symptoms in decreasing order of
frequency as follows: abdominal pain, palpable tu-
mor, ascites, weakness and loss of weight, abdominal
distension, bowel irregularity, anemia.
A case of multiple fibrous tumors arising from
the greater omentum is reported. Such tumors are
usually benign, are almost always an incidental
finding at operation and are rarely diagnosed pre-
operatively. They are either asymptomatic or may
produce symptoms of torsion of their pedicles or
by involving themselves in adhesive processes to
produce bowel obstruction or, in some instances,
by producing ascites.
255 Farmers Lane, Santa Rosa, California 95405.
1. Ackerman, L. V.: (1954), Atlas of Tumor PathoIogy,
Sect. VI Fasc. 23 & 24, 97 Washington: Armed Forces Insti-
tute of Pathology.
2. Castleman, B.: Case records of the Massachusetts Gen-
eral Hospital, N.E.J.M., 265:1064-68, Nov. 23, 1961.
3. Crowley, D. F.: Primary torsion of the omentum, J.
Iowa State M. Soc., 50:608-10, Oct. 1960.
4. McGahan, J. J.: Acute ideopathic infarction of the
omentum, Rocky Mountain M. J., 56:37-38, Dec. 1959.
5. Ransom, H. R., and Samson, P. C.: Annals of Surgery,
6. Robb, W. A. T.: Lipsosarcoma of the greater omentum,
Brit. J. Surg., 47:537-9, March 1960.
7. Smith, H. F.: Peritoneal fibromatosis presenting as an
acute abdominal emergency, Brit. J. Surg., 208:161-2, Sept.
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