Pelvic retroperitoneal leiomyoma
Hui-Wen Lin, M.D.a, Wei-Chih Su, M.D.b, Ming-Song Tsai, M.D.a,
Mei-Leng Cheong, M.D.a,c,d,*
aDepartment of Obstetrics and Gynecology, Cathay General Hospital, Taipei, Taiwan;bDivision of Gastroenterology, Department of
Medicine, Buddhist Tzu-Chi General Hospital, Taipei Branch, Taipei County, Taiwan;cGraduate Institute of Biochemical Sciences,
National Taiwan University, Taipei, Taiwan;dInstitute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
A 26-year-old woman presented with chronic constipation and acute abdominal pain. The diagnostic workup
homogeneous pelvic tumor with rectal compression. Retroperitoneal leiomyoma was suspected on imaging
studies and finally confirmed after tumor excision and immunohistochemical staining.
© 2010 Elsevier Inc. All rights reserved.
A 26-year-old woman suffered from constipation for 3
years. She had never had sexual experience. She presented
at the emergency room with severe lower abdominal pain.
Physical and laboratory examinations were unremarkable.
Computer tomography (CT) demonstrated a pelvic mass of
8 ? 7 ? 7 cm located posterior to the ureters with homo-
geneous soft tissue density and compression of the rectum
(Fig. 1). Colonoscopy revealed a partial rectal obstruction at
the rectosigmoidal junction without mucosa involvement
(Fig. 2). Because the density was similar to the uterus, a
uterine tumor was suspected. A primary uterine tumor was
thought to be unlikely, however, because of the findings on
transabdominal ultrasonography (Fig. 3); hence, a leiomy-
oma arising from the retroperitoneum was highly suspected.
Laparotomy was performed, with the finding of a posterior,
pelvic retroperitoneal, encapsulated solid tumor without a
uterine connection but adhesive to the rectum. General
surgeons were consulted, and the surgical procedures in-
cluded excision of the tumor and resection of the 6-cm
involved portion of rectum. The rectum was immediately
reconnected via an end-to-end anastomosis. Pathologic ex-
amination revealed a typical leiomyoma with focal myxoid
changes primarily originated from the retroperitoneum and
unremarkable rectum. No significant nuclear atypia or mitotic
activity was seen. The tumor cells were positive for smooth
muscle actin and desmin but negative for CD117, CD34, and
S-100 protein by immunohistochemical staining. There was no
recurrence in the 16 months following surgery.
Primary retroperitoneal tumors are quite rare, and most are
malignant.1Between 1941 and 2007, only 105 cases of retro-
peritoneal leiomyoma were reported.2Besides leiomyoma, the
different diagnosis of a benign retroperitoneal neoplasm in-
cludes mature teratoma, schwannoma, lipoma, lymphangioma,
and neurofibroma.3Preoperative diagnosis can be difficult be-
cause of the rarity and nonspecific clinical presentation of this
neoplasm. It may be asymptomatic or cause abdominal full-
ness, weight loss, pelvic pain, and symptoms resulting from
compression of adjacent organs. Retroperitoneal neoplasms
may also present suddenly, with acute onset of pain or hypo-
volemic symptoms because of spontaneous retroperitoneal
hemorrhage from the tumor.4
* Corresponding author. Tel.: 886-928123206; fax: 886-2-27082121
E-mail address: email@example.com
Manuscript received March 4, 2009; revised manuscript May 4, 2009
0002-9610/$ - see front matter © 2010 Elsevier Inc. All rights reserved.
The American Journal of Surgery (2010) 199, e36–e38
The pelvis is the most common location for retroperito-
neal leiomyoma (73%).2Clinical imaging of ultrasonogra-
phy, CT, or magnetic resonance imaging can help in the
assessment of the tumor and its relation to other pelvic
organs. Leiomyomas adjacent to the uterus can mimic ad-
nexal malignancies if complex cystic degeneration is ob-
served. Hayasaka et al3reported that mature teratoma
showed fat density, water density, and calcification;
schwannoma showed water density and occasional septal
contrast enhancement; leiomyoma showed soft tissue den-
sity, contrast enhancement, and occasional water density;
lipoma showed fat density and calcification; and lymphangi-
oma and neurofibroma showed water density. They con-
cluded that internal homogeneity, fat density, cyst forma-
tion, and calcification are important predictors of primary
benign retroperitoneal tumors on CT. Gastrointestinal stro-
mal tumors may also be one of the differential diagnoses;
large gastrointestinal stromal tumors usually appear as het-
erogeneous masses with enhancing borders of variable
thickness and irregular central areas of fluid. We suspected
that the lesion was a leiomyoma because of its characteristic
images. However, it is hard to differentiate leiomyoma from
leiomyosarcoma on the basis of imaging features alone,
even though extensive central necrosis, invasive growth,
and a heterogeneous appearance are suggestive of leiomy-
osarcoma,5and the distinction between leiomyomas and
small gastrointestinal stromal tumors with homogeneous
density is also radiologically difficult, depending on the
immunohistochemical findings: the former stains positive
for smooth muscle actin but negative for CD117 and CD34,
and vice versa. Our patient presented with a solitary tumor
independent of the uterus, but ?40% of patients have concur-
rent or histories of uterine leiomyoma,2which is another clue
to the preoperative diagnosis of retroperitoneal leiomyoma.
Compared with CT, magnetic resonance imaging is more use-
ful for characterizing these tumors, because, regardless of their
anatomic locations, classic leiomyomas have signal intensity
similar to that of smooth muscle on images obtained with any
magnetic resonance pulse sequence.5
the mainstay for diagnosis and treatment. For the expectant man-
agement of asymptomatic patients refusing operation, ultrasonog-
raphy-guided or CT-guided fine-needle aspiration or biopsy may
be histologically beneficial. Like uterine leiomyoma, the progno-
sis of retroperitoneal leiomyoma is favorable. Thirty of 32 female
patients were alive without disease after an average period of 140
CT revealing a pelvic tumor (asterisk) with homogeneous soft
tissue density similar to the uterus (arrowhead) and posterior to the
bilateral ureters (arrow).
Transverse view (A) and coronal view (B) of contrast
row) of the rectum without mucosa involvement.
Colonoscopy showing an external compression (ar-
vealing a normal uterus without uterine leiomyoma.
Longitudinal view of transabdominal ultrasound re-
e37Lin et alPelvic retroperitoneal leiomyoma
months or died of unrelated causes after an average of 145 Download full-text
months; although 2 had local recurrence, neither patient with
recurrence demonstrated disease progression on follow-up.6
In conclusion, our patient demonstrated a rare case of
primary pelvic retroperitoneal leiomyoma with typical im-
aging features that led to preoperative suspicion.
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retroperitoneal leiomyosarcomas. Am J Surg Pathol 2001;25:1355–63.
e38The American Journal of Surgery, Vol 199, No 4, April 2010