Vol.2, No.6, 366-369 (2013) Case Reports in Clinical Medicine
http://dx.doi.org/10.4236/crcm.2013.26098
A case report on retroperitoneal PNET/EWS
Zhanqiang Zhang, Honglan Yu, Yingying Shi, Hanping Shi*
Department of Surgery, The First Affiliated Hospital, Sun Yet-sen University, Guangzhou, China;
*Corresponding Author:
Received 12 June 2013; revised 20 July 2013; accepted 1 August 2013
Copyright © 2013 Zhanqiang Zhang et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Primitive neuroectodermal tumor (PNET) and
Ewing’s sarcoma (EWS) are small round cell
tumors occurring mainly in children and ado-
lescents, rarely in adults. It can occur in multiple
tissues and organs including kidney, adrenal,
bladder, liver, small intestine, colon and rectum,
with a preferred location within the chest area, in
the limbs and around the spine, but with rare
cases of abdominal, pelvic or retroperitoneal.
Here we present a case of the retroperitoneal
PENT/EWS in a 38-year-old man and we discuss
the clinical features, histopathological charac-
teristics, diagnosis, treatment and prognosis.
Keywords: Retroperitoneal; Sarcoma; Primitive
Neuroectod er ma l T um or; Ewing’s Sarcoma
1. INTRODUCTION
Primitive neuroectodermal tumor (PNET) and Ewing’s
sarcoma (EWS) are small round cell tumors occurring in
the soft tissues and bones, but rarely in the abdominal
cavity, pelvic and retroperitoneal. Here we present a case
report on the retroperitoneal PENT/EWS in our hospital,
in conjunction with literature review on the topic.
2. CASE PRESENTATION
A male subject of 38 years old, who had left upper
quadrant mass accompanied with pain for 1.5 years and
with enhanced pain since the past 20 days, was admitted
into our hospital on July 2, 2007. The subject received
left kidney + left retroperitoneal tumor partial resection
after revealing a bulky left retroperitoneal tumor by CT
and MR examination for his left upper abdominal pain in
December 2005 at a local hospital. He then began a
chemotherapy program because of the PNET diagnosed
by postoperative pathology in January 13, 2006. The
chemotherapy regimen was ifosfamide 4.0 g on day 1-4
+ epirubicin 100 mg on day 1, 2, and 4. Later, he was
admitted into our hospital after a 8 × 9.6 cm2 cystic
space-occupying lesion in his left kidney had been re-
vealed by CT. The results based on consultation on the
pathological datasheet collected from the hospital where
he received the surgery and chemotherapy indicated that
the tumor cells were small and round with strongly
stained nuclei, thin chromatin, poorly defined nucleoli,
and shrank cytoplasm. The tumor cells were diffused,
partly displaying the daisy-like structure. Immunohisto-
chemistry: CD56 and CD99 (+) large-sheet structure tu-
mor cells, CgA and Syn (+) small number tumor cells,
LCA (−), EMA and CK (−), vimentin and CD34 (−), Ag
tumor cells missing reticular fibers, diagnosed as PENT/
EWS. Laparotomy on May 25, 2006 after appropriate
preoperative preparation displayed the left upper quad-
rant mass up to the diaphragm, down to the left iliac
fossa, medial to the right side of the abdominal aorta,
lateral to the left paracolic gutter. The lump felt hard and
looked smooth and glossy, and was located deep to the
waist big muscle closed to spleen. Thus, a complete re-
section of the whole lump tissue along with the whole
spleen and the diaphragm area adhered and infiltrated by
the tumor. The patient recovered well after the surgery
and was discharged without complications. He continued
the same chemotherapy program at the local hospital. He
experienced recurrence of left upper quadrant pain 20
days ago. MR displayed at left upper quadrant retroperi-
toneal tumor; he was then readmitted to our hospital.
Physical examination: abdomen slightly bulged, left up-
per quadrant palpable mass which was ill-defined with
tenderness and poor mobility, but without other abnor-
malities. Upon completion of all necessary preoperative
routine examination, no obvious abnormalities were found.
The markers for digestive system tumors AFP, CA19-9,
CEA, and CA125 were all at normal levels. CT showed a
round mass either on the left kidney area or retroperito-
neal area, with the upper mass measuring 8 × 8.9 × 8.4
cm3 and the lower one measuring 7 × 7.1 × 5.4 cm3; with
unclear boundary and adhesion to neighboring tissues,

Z. Q. Zhang et al. / Case Reports in Clinical Medicine 2 (2013) 366-369 367
close to the diaphragm; the lower lump wrapped iliac
artery and adhered to gastrointestinal tract. Otherwise,
the patient was in good condition without significant
surgical contraindications. After all preoperative prepara-
tion, we planned to conduct complete resection of the
tumor and its adhesion diaphragmatic with patch repair
and graft replacement for the tumor in the lower position
had iliac artery adhesions. However, in the morning of
the day for operation, the patient had sudden sinus
tachycardia with heart rate of 120 bpm at the time of
indwelling nasogastric tube. The surgery had to be inter-
rupted. The patients were under monitoring for several
days. His heart rate decreased, but remained relatively
high compared to baseline heart rate. The patient and his
family members asked for provisional discharge. After-
wards, his tumor grew rapidly, but because of the diffi-
cult financial situation, he has not received surgery any
more. He died of gastrointestinal obstruction, malnutri-
tion, and cachexia 37 days after being discharged.
3. DISCUSSION
3.1. Overview
PNET and EWS are malignant tumors composed of
small round cells, frequently occur in the soft tissue and
bone but are very rare clinical cases. They have a com-
mon neuroectodermal origin, with similar morphological
conformation, specific chromosomeal translocation which
is related to the EWS gene on chromosome 22, belong-
ing to the PNET/EWS family tumors [1]. PNET and
EWS were once believed to be different types of tumors
because of their different differentiations: PNET belongs
to neuroectodermal differentiation whereas EWS tends to
be undifferentiated. With the advances of immunohisto-
chemistry, electron microscopy, and genetic pathology,
bone Ewing’s sarcoma, bone Ewing’s sarcoma, the pe-
ripheral neuroepithelioma or primitive neuroectodermal
tumor, Askin’s tumor, as well as other types of tumors
with their classification still in debate are now all con-
sidered as PNET/EWS family tumors [2-4]. A growing
number of studies suggest that between PNET and EWS
there are no significant differences in terms of their
treatment and prognosis. The first case of PNET/EWS
family tumors was reported in 1918 by Stout. In recent
years, with the development of immunohistochemistry
and electron microscopy techniques, our understanding
of PNET/EWS family tumors have been gradually deep-
ening and reports on this condition have been steadily
increasing. PNET/EWS occurs mainly in children and
adolescents, rarely in adults. It can occur in multiple tis-
sues and organs including kidney, adrenal, bladder, liver,
small intestine, colon and rectum, with a preferred loca-
tion within the chest area, in the limbs and around the
spine, but with rare cases in abdominal, pelvic or retrop-
eritoneal.
3.2. Clinical Manifestations
Clinical manifestations depend on the site and the size
of the tumor, and the invasion of the surrounding organs.
The rapid growth accompanied by pain, lumps, and
compression symptoms caused by the tumor is the most
common manifestation [5]. Other manifestations include
fatigue, weight loss, fever, and various gastrointestinal
symptoms such as abdominal distension, nausea, and
vomiting.
3.3. Auxiliary Examination
There have not been any clinical laboratory tests and
specific biomarkers for this type of tumor. B ultrasound,
CT, and MR are mainly used to depict tumor internal
structure, the scope of violations as well as relations with
the surrounding tissue, and meanwhile to provide the
information as tumor metastasis, which is of paramount
clinical importance for preoperative evaluation of the
resection scope and the anticipated efficacy. Imaging
often shows soft tissue mass, invasive growth, tendency
to invade surrounding tissue, and unclear boundaries
with the surrounding tissue structure. In addition to the
small size, the tumor generally has uneven density. Un-
der CT, the tumor mostly shows uneven density with
visible internal cystic and necrosis, which are worsened
by tumor enlargement [6]. If a tumor is seen in the pre-
ferred sites with obvious invasion, easy liquefaction and
necrosis, as well as incomplete capsule and the separator
inside the tumor, especially if when obvious tumor
thrombus can be seen in the surrounding intravascular,
then the possibility of PNET should be considered [7].
The definite diagnosis still relies on biopsy and patho-
logical examination. To prevent the spread of the tumor
and the needle tract transfer, preoperative percutaneous
biopsy is generally not recommended, unless the tumor is
unresectable and needs radiotherapy and chemotherapy
[8].
3.4. Pathology
Tumor specimens: oval, lobulated or irregular in shap;
infiltrative growth; incomplete capsule, size ranging
from 3 cm × 2cm × 1 cm to 40 cm × 20 cm × 5 cm; sec-
tions are gray or sallow in color, solid and brittle or soft,
fish-like hemorrhagic necrosis in texture [9]. Morpho-
logical characteristics include malignant tumor mass
with small round cells, visible small focal necrosis and
spread necrosis under a light microscope, which may or
may not form the Homer-Wright rosettes. CD99 (MIC2)
is uniformly and diffusely expressed on the cell mem-
brane of the tumor, and vimentin, NSE, Syn, of Cag, NF,
and S-100 are also expressed to varying abundances.

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368
Glycogen granules or nerve secretory granules can be
seen under an electron microscope [9,10].
From the molecular pathological view, PNET/EWS
have the same t(11; 22) (q24; q12), or less t(21; 22) (q22;
q12) or t(7; 22) (p22; q12). All these chromosomal rear-
rangements fuse the EWS gene on chromosome 22 to
FLI21 ERG or ETV1 gene members of the ETS tran-
scription factor family, resulting in EWS/FLI21, EWS/
ERG or EWS/ETV1 fusion genes, leading to tumori-
genesis. 95% of the tumors can be detected by RT-PCR
and FISH with high sensitivity and specificity [11].
Identification and diagnosis of this type of tumor pri-
marily relies on comparisons with other intra-abdominal
and retroperitoneal soft tissue tumors, including the loca-
tion, age, tumor morphological alterations, immunohis-
tochemical illustration, and genetic traits.
3.5. Treatment and Prognosis
PNET/EWS is a systemic disease and its therapy re-
quires comprehensive treatment, including surgery, ra-
diotherapy, chemotherapy and biological therapy. There
is no uniform regimen for intraperitoneal or retroperito-
neal PNET/EWS. Rud et al. [12] and Covelli et al. [13]
suggested that the surgery may be more important for
EWS outside bone than EWS in the bone and total resec-
tion yields better prognosis. Based on the literature,
complete surgical removal may be the most effective
means for cure; even for patients with local recurrence, if
possible, surgical treatment should be implemented. In
order to ensure complete resection, removal of some ad-
jacent organs, the most commonly kidney, adrenal, colon,
pancreas, and spleen, is often necessary. With the devel-
opment of vascular surgery, resection of involved vessels
and implantation of artificial blood vessels may be coap-
plied, though the long-term efficacy and benefits await
further studies to confirm.
As far as radiotherapy and chemotherapy, there are
different views. Kinsella et al. [14] believed that high
doses of local radiotherapy and VAC procedures are
adequate for EWS outside bone and total surgical resec-
tion may be unnecessary. Local adjuvant radiotherapy
after complete resection cannot significantly reduce the
local recurrence because of high doses and side effects
that require stringent protective measures [12,15]. Ven-
kitaraman et al. [16] proposed that intensive chemother-
apy is necessary after complete resection of the tumor or
radiotherapy with doses >50 Gy, for patients with PNET/
EWS sarcoma outside bone in order to obtain good effect.
Of 14 PNET/EWS patients without metastases who un-
derwent combinational chemotherapy (5 with VAC pro-
cedures, 5 with VACA procedures, four with VAC/IE
procedures), 8 were cured, 2 partially cured, and 4 had
progressive deterioration [16].
Venkitaraman et al. [16] believed that high hemoglo-
bin, low lactate dehydrogenase, VAC/IE chemotherapy,
and complete response to chemotherapy are the factors
for raising tumor-free survival rate and overall survival
rate. Martin et al. [15] considered the initial perform-
ance of tumor (primary or recurrent) is an important pro-
gnostic factor, whereas tumor location, size, and age
make no statistical significance [15,16]. PNET/EWS pa-
tients without metastatic who received combination ther-
apy had 5-year survival rate of 60% and overall survival
rate of 30% [16]. Aggressive PNET/EWS causes distant
metastases at early stages, frequent local recurrence and
regional lymph nodes, lungs, liver, bone and bone mar-
row metastasis, and has poor prognosis with the median
survival time of about two years; the leading cause of
death is metastasis to the lung, bone, liver and other or-
gans.
4. CONCLUSION
The abdominal cavity and retroperitoneal PNET/EWS
are relatively rare, but they grow rapidly in larger size,
oppress surrounding organs and large vessels, and make
surgical resection difficult. It is often in high degree of
malignancy and already has widespread subclinical me-
tastasis at the time of going to a clinic. Moreover, it can
quickly transfer to everywhere throughout the body ren-
dering poor prognosis. Clinicians should be highly alert
to this condition. Imaging is the primary means of early
detection and early diagnosis. Complete surgical resec-
tion may be the most effective way of cure. Whenever
possible, surgery should be implemented even in patients
with local recurrence. In order to ensure complete re-
section, removal of any neighboring organs, most com-
monly kidney, adrenal, colon, pancreas, spleen, and so on,
may be required. With the development of vascular sur-
gery, resection of involved vessels and implantation of
artificial blood vessels may be conducted. The efficacy
of radiotherapy is still unclear. Future studies are war-
ranted to develop surely effective surgical treatment op-
tions and preoperative/postoperative adjuvant therapies.
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