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\begin{document}

\title{Undifferentiated Pleomorphic Sarcoma of the Sigmoid Colon: A case report}



\author[1]{Yuxia Yang}%
\author[2]{Yuchang Hu}%
\author[2]{Mengxi He}%
\author[1]{Min Cheng}%
\affil[1]{China Three Gorges University}%
\affil[2]{Yichang Central People's Hospital}%


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  \date{May 24, 2024}


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Undifferentiated Pleomorphic Sarcoma of the Sigmoid Colon: A case report

\textsuperscript{1,2, *} Yuxia Yang, \textsuperscript{1,2}Yuchang
Hu,\textsuperscript{2}Mengxi He,\textsuperscript{1,2}Min Cheng

The First College of Clinical Medical Science, China Three Gorges
University.

Department of Pathology, Yichang Central People's Hospital, Yichang,
China)

Corresponding author: Yuxia Yang

Corresponding author address:\emph{2916087819@qq.com}

Yuxia Yang:\emph{2916087819@qq.com} , Master's Degree

Yuchang Hu:\emph{huyuchang@hotmail.com}, Master's Degree

Mengxi He: \emph{452818936@qq.com}, Master's Degree

Min Cheng: \emph{371227344@qq.com}, Master's Degree

Funding information: This study did not receive any funding in any form.

Acknowledgements: Thanks to my tutor, family and colleagues.

Ethics statement: Our institution does not require ethical approval for
reporting individual cases or case series.

Statement of informed consent: Written informed consent was obtained
from the patient for their anonymized information to be published in
this article.

Conflict of interest statement: All authors declare that they have no
competing interests.

Data sharing statement: Data sharing is not applicable to this article
as no new data were created or analyzed in this study.

Key clinical message: Elderly patients with abdominal pain are easy to
be misdiagnosed as gastrointestinal cancer. The possibility of UPS
should be recognized in clinical work.

Abstract: UPS is the most common soft tissue malignant tumor in the
elderly. It usually occurs in the proximal limbs and retroperitoneum,
and is usually manifested as a progressively enlarged painless mass. Due
to its histological aggressiveness, it has a poor prognosis, with a
five-year survival rate of less than 50\% and frequent metastasis or
recurrence. UPS in the colon is rare. Due to its special location,
atypical clinical manifestations, and lack of characteristic
pathological signs, the diagnosis is usually a diagnosis of exclusion.
Early and complete resection of the tumor is the main treatment for UPS.
Although some studies have shown that postoperative adjuvant
radiotherapy and chemotherapy have a certain local control rate, the
effect of radiotherapy and chemotherapy is not completely certain, and
more cases are needed to further study its efficacy.

Key words: Undifferentiated pleomorphic sarcoma, colon, treatment.

Introduction

Undifferentiated pleomorphic sarcoma UPS is the most common soft tissue
malignant tumor in the elderly. It usually occurs in the proximal limbs
and retroperitoneum, and is usually manifested as a progressively
enlarged painless mass\textsuperscript{{[}1{]}}. Due to its histological
aggressiveness, it has a poor prognosis, with a five-year survival rate
of less than 50\% and frequent metastasis or recurrence. UPS in the
colon is rare. Due to its special location, atypical clinical
manifestations, and lack of characteristic pathological signs, the
diagnosis is usually a diagnosis of exclusion. Early and complete
resection of the tumor is the main treatment for UPS. Although some
studies have shown that postoperative adjuvant radiotherapy and
chemotherapy have a certain local control rate\textsuperscript{{[}2{]}},
the effect of radiotherapy and chemotherapy is not completely certain,
and more cases are needed to further study its efficacy.

Case report

A 54-year-old man was admitted to the hospital due to left abdominal
pain for 1 week. The pain was persistent and tolerable, without other
accompanying symptoms. Abdominal Computed tomography (CT) scan showed a
huge mass of mixed density shadow in the lower abdomen and pelvis, the
size was about 16.3*6.8cm. Enhanced scan showed uneven enhancement of
the lesion, and the mass was closely related to the intestine, and the
boundary was not clear (Figure 1). The tumor was suspected as
gastrointestinal stromal tumor. During the operation, a new tumor was
found on the serosal surface of the sigmoid colon, with the size of
19cm*14cm*10cm, and no metastatic lesions were found around it (Figure
2). Gross examination showed that the tumor was encapsulated on the
surface, with rich blood vessels. The cut surface was gray white and
gray red, which was cystic and solid, soft in texture, containing a
large amount of mucus, accompanied by necrosis and hemorrhage in some
areas. Microscopically, the tumor cells were arranged disorderly,
irregularly shaped, varying in size, with obvious atypia, numerous
mitotic figures, prominent nucleoli, and a large number of tumor giant
cells and multinucleated tumor giant cells (Figure 3). The tumor stroma
was rich in blood vessels with myxoid degeneration.
Immunohistochemically, the tumor cells showed a high Ki-67 proliferation
index, focally positive for CD34 and S-100 (Figure 4), and a mutant
expression pattern of P53. The pathological diagnosis was high-grade
undifferentiated pleomorphic sarcoma with negative margins (no tumor
cells in the margins). The patient did not receive any adjuvant therapy
after surgery. Three months later, CT scan showed multiple mixed density
shadows in the lower abdomen and pelvis, considering tumor metastasis or
recurrence.

Discussions

High-grade undifferentiated pleomorphic sarcoma (UPS), formerly known as
malignant fibrous histiocytoma (MFH), is characterized by a
progressively enlarged, painless mass\textsuperscript{{[}1{]}}. It
mainly occurs in the soft tissues of the extremities and the
retroperitoneum, and rarely occurs in the digestive tract. Grossly, the
tumor was a solitary nodule with a fish-like, offwhite to brown cut
surface. Hemorrhage and necrosis were common\textsuperscript{{[}1{]}}.
UPS of the colon may originate from mesenchymal stem cells in the
mesentery\textsuperscript{{[}3{]}{[}4{]}}. Histologically, UPS of the
colon is characterized by large atypical cells with more mitoses and
prominent nucleoli. The atypical cells can show different morphologies,
including pleomorphic, myxoid, xantomatous, giant cell and angiomatoid
types. They are broadly positive for CD68 and vimentin, and focally
positive for CK and EMA. Due to its high degree of malignancy and strong
invasion, it is easy to relapse and distant metastasis after surgery.
Distant metastasis is most common in lung, followed by bone and
liver\textsuperscript{{[}5{]}{[}6{]}}. Wide resection with negative
resection margins (RO resection) is the main treatment for UPS, and
negative resection margins help to reduce the risk of tumor recurrence.
However, the recurrence rate of UPS is still high, and the 5-year
survival rate is less than 50\%. Tumor size, location, degree of
differentiation and completeness of surgery are closely related to the
prognosis of UPS\textsuperscript{{[}5{]}}. The effects of postoperative
adjuvant radiotherapy and chemotherapy have not been reported, but some
studies have shown that compared with surgery alone, although adjuvant
radiotherapy and chemotherapy can't improve the overall survival rate,
they can significantly improve the local control rate of high-grade soft
tissue sarcoma\textsuperscript{{[}2{]}}.

Conclusions

Due to the low incidence of UPS, there are few cases available for
clinical study, and the effective treatment of this disease still needs
further research. UPS arising from the colon is rare. For patients with
abdominal pain and obvious abdominal mass, the possibility of UPS should
be considered. Early and complete resection of the mass is the main
treatment.

Author contributions:

Conceptualization: Yuchang Hu, Yuxia Yang

Data curation: Mengxi He, Yuxia Yang

Supervision: Mengxi He

Software: Yuchang Hu, Min Cheng

Writing -- original draft: Yuxia Yang, Mengxi He, Min Cheng

Writing -- review \& editing: Yuchang Hu, Yuxia Yang

Abbreviations:

UPS= Undifferentiated pleomorphic sarcoma

CT= Computed tomography

MFH= Malignant fibrous histiocytoma

EMA= Epithelial membrane antigen

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