case report schwannoma of the colon: report of a case and ... · case and review of the literature...
TRANSCRIPT
Stromal tumors of gastrointestinal tract include a
variety of primary mesenchymal tumors of the
gastrointestinal tract, such as leiomyoma, leiomyo-
sarcoma, leiomyoblastoma, and schwannoma.1
Schwannomas are rare tumors derived from Sch-
wann cells, which form the neural sheath. Gastro-
intesinal schwannomas are rare and most of them
originate in the stomach or the small intestine. Sch-
wannomas of the colon are extremely rare. Few case
reports have described the occurrence of schwan-
nomas in the colon.1-4
Case Report
Our patient was a 45-year-old woman whose gen-
eral health condition was good before the appearance
of symptoms. She visited our gastrointestinal clinic in
June 2005 complaining of bloody stool with blood
clots and mucus content for 1 week, with several epi-
sodes of mild diarrhea. She denied any abdominal
pain, body weight loss, or recent change in bowel
habit. She also denied any medical or operative his-
tory or family history of cancer. Her vital signs were
normal and physical examination were unremarkable.
Flexible sigmoidoscopy revealed a huge yellow bulg-
ing intra-luminal tumor obstructing the lumen at 50
cm above the anal verge (Fig. 1). A biopsy of the tu-
mor was obtained and pathology showed inflamma-
tory exudates, necrotic debris, acute and chronic in-
flammation, and granulation tissue formation. Though
no malignancy was found in the biopsy specimen, en-
doscopic findings indicated colon cancer, so the pa-
tient was referred to a proctologist for operation. Lab-
oratory tests and other examinations demonstrated
only mild anemia (hemoglobin, 10.0 g/dL). Dou-
J Soc Colon Rectal Surgeon (Taiwan) December 2008
Case Report
Schwannoma of the Colon: Report of a
Case and Review of the Literature
Hsin-Yuan Hung1
Jy-Ming Chiang1
Jinn-Shiun Chen1
Reiping Tang1
Tse-Ching Chen2
1Division of Colon and Rectal Surgery,
Chang Gung Memorial Hospital, Lin-Kou,
Taiwan2Department of Pathology, Chang Gung
Memorial Hospital, Lin-Kou, Taiwan
Key Words
Gastrointestinal schwannoma;
Colon;
Immunohistochemistry
Schwannomas of the colon are extremely rare, and it is necessary to treatthem by radial excision with a wide margin because of their tendency torecur locally and become malignant if inadequately treated. In the presentstudy, we report a rare case of a colonic schwannoma that was success-fully treated by surgical resection in our department. Immunohistochemi-stry revealed that the tumor was positive for S-100 and negative forC-KIT, smooth muscle actin, CD21, CD34, and CD35. The patient wastherefore diagnosed with a schwannoma, not a gastrointestinal stromal tu-mor(GIST). We report the findings of endoscopy, radiology, and pathol-ogy in a patient with colonic schwannoma. The literature on colonicschwannomas has been reviewed.[J Soc Colon Rectal Surgeon (Taiwan) 2008;19:128-132]
Received: September 25, 2008. Accepted: December 31, 2008.
Correspondence to: Dr. Jinn-Shiun Chen, M.D. Division of Colon and Rectal Surgery, Chang Gung Memorial Hospital 199, Tung
Hwa North Road, Taipei, Taiwan. Tel: +886-3-3281200 ext. 2101; Fax: +886-3-3278355.
128
ble-contrast barium examination revealed a huge
ovoid intra-luminal mass in the mid-portion of the de-
scending colon, which resulted in partial obstruction
of the colon. (Fig. 2). Abdominal computed tomogra-
phy (CT) using oral and intravenous contrast agents
revealed a soft tissue mass at the junction of the de-
scending and the sigmoid colon.
No definite paraaortic and pelvic lymphadenoathy
or definite hepatic metastasis was noted (Fig. 3).
In July 2005, the patient underwent an operation
in which a segment about 26 cm-long of the left colon
was resected. On sectioning, a 5*4*3 cm yellowish
white polypoid mass was found. The tumor consis-
tency was elastic, and the tumor originates from a
muscular layer with focal ulcerated overlying mu-
cosa. Microscopic examination of the neoplasm re-
vealed a tumor in the muscular wall composed of in-
terlacing bundles of spindle cells (Fig. 4). Mild nu-
clear pleomorphism and a mitotic activity of 6/50
HPF were noted. Immunohistochemical staining re-
vealed that the tumor cells were positive for S-100
(Fig. 5) and negative for C-KIT, smooth muscle actin,
CD21, CD34, and CD35. The patient was therefore
diagnosed with a colon schwannoma, not a gastroin-
testinal stromal tumor (GIST).
The patient recovered well. She was discharged
on the eighth postoperative day and reqularly fol-
lowed up at the clinic for 2 years; no recurrence was
found.
Discussion
Schwannomas usually present as well-circum-
scribed masses attached to peripheral nerves, cranial
nerves, or spinal nerve roots.5 Schwannomas of the
colon and rectum are extremely rare. Primary schwan-
nomas of the bowel are rare and occur most frequently
Vol. 19, No. 4 Desending Colon Schwannoma 129
Fig. 1. Colonoscopic picture of descending colon Schwan-noma.
Fig. 2. Double-contrast barium examination revealed ahuge ovoid intra-luminal mass in the mid-portion ofthe descending colon (arrow).
Fig. 3. Computed tomography scan revealed a polypoid tu-mor at descending colon.
in the stomach. Colonic schwannoma was first re-
ported by Lamy et al.6 A large number of schwannoma
cases have been reported since 1910. Ito et al re-
viewed 37 cases of schwannomas of the large intestine
in 1996.7
Colonic schwannomas tend to be circumscribed,
but are also non-encapsulated nodular or ovoid mass-
es with a polypoid component. They present as poly-
poid intra-luminal lesions, and the overlying mucosa
may have ulcerations. The tumor specimen obtained
by forceps biopsy is not always sufficient for his-
tological diagnosis. In our patient, the biopsy showed
ulceration with granulation tissue. The patient pre-
sented with symptoms, including abdominal pain,
bowel obstruction, and rectal bleeding.8
Colonic schwannomas are slow-growing tumors
and are usually solitary. These lesions are character-
ized by a peripheral lymphoid cuff, which may con-
tain germinal centers.3 Routine hematoxylin and eosin
staining does not enable differentiation between ne-
urogenic and myogenic tumors. Immunohistochemi-
cal staining is a new reliable technique for making a
correct differential diagnosis. In our patient, the tumor
cells were positive for S-100 protein and negative for
CD34 and smooth muscle actin. Gastrointestinal sch-
wannomas are reported to be commonly associated
with a diffuse S-100 protein reaction and peri-tumoral
lymph follicles.9
Most schwannomas are benign and symptomatic,
but the possibility of malignant degeneration does ex-
ist and is directly related to the tumor dimensions.
Radical surgical treatment is the gold standard in all
cases. The role of chemotherapy and radiotherapy in
treating schwannomas remains uncertain.10,11
In our patient, the tumor size was large (5 cm) and
the mitosis count was 6 per 50 high-power fields;
therefore, we diagnosed this tumor as having high ma-
lignancy potential. Since histological criteria for de-
fining the grade of malignancy of gastrointestinal
schwannomas have not yet been determined, and still
their metastatic potential is not known, careful obser-
vation of the patient’s postoperative course should be
necessary.
References
1. Prevot S, Bienvenu L, Vaillant JC, de Saint-Maur PP. Benign
schwannoma of the digestive tract: a clinicopathologic and
immunohistochemical study of five cases, including a case of
esophageal tumor. Am J Surg Pathol 1999;23:431-6.
2. Sasatomi T, Tsuji Y, Tanaka S, et al. Schwannoma of the sig-
moid colon: report of a case. Kurume Med J 2000;47:165-8.
3. Skopelitou AS, Mylonakis EP, Charchanti AV, Kappas AM.
Cellular neurilemoma(schwannoma) of the descending colon
mimicking carcinoma: report of a case. Dis Colon Rectum
1998;41:1193-6.
4. Tomozawa S, Masaki T, Matsuda K, et al. A schwannoma of
the cecum: case report and review of Japanese schwannomas
in the large intestine. J Gastroenterol 1998;33:872-5.
5. Burns DK. The nervous system; neoplasms of the peripheral
nervous system. Basic pathology. New York: WB Saunders;
130 Hsin-Yuan Hung, et al. J Soc Colon Rectal Surgeon(Taiwan) December 2008
Fig. 4. High power microscopic view revealed a tumorcomposed of interlacing bundles of spindle cells.
Fig. 5. Immunohistochemical staining: strong staining ofS-100.
1997:743-4.
6. Lamy J, Bricot R, Bureau H. Voluminous isolated schwan-
noma of the transverse colon. Mars Chir 1962;14:436-7.
7. Ito S, Matsumoto H, Kogure H, et al. A case of transverse co-
lon schwannoma. J Jpn Soc Colo-proctol 1996;49:139-43.
8. Miettinen M, Shekitka KM, Sobin LH. Schwannomas in the
colon and rectum: a clinicopathologic and immunohisto-
chemical studyof 20 cases. Am J Surg Pathol 2001;25:846-
55.
9. Daimaru Y, Kido H, Hashimoto H, et al. Benign schwannoma
of the gastrointestinal tract: Aclinicopathologic and immuno-
histochemical study. Hum Pathol 1981;19:257-64.
10. Miettinen M, Sarlomo-Rikala M, Lasota J. Gastrointestinal
stromal tumours. Ann Chir Gynaecol 1998;87:278-81.
Pollock J, Morgan D, Denobile J, Williams J. Adjuvant radio-
therapy for gastrointestinal stromal tumor of the rectum. Dig
Dis Sci 2110;46:268-72.
11. Fotiadis CI, Kouerinis IA, Papandreou I, Zografos GC,
Agapitos G. Sigmoid schwannoma: a rare case. World J Gas-
troenterol 2005;11:5079-81.
Vol. 19, No. 4 Desending Colon Schwannoma 131