This document presents a case report of a rare dedifferentiated retroperitoneal liposarcoma that caused bowel obstruction. It describes the patient's presentation, surgical findings, and histopathological examination results. Key findings included lipoblasts and spindle cells on microscopy, as well as genetic abnormalities involving CDK4 and MDM2 amplification. While surgery is the primary treatment, targeted therapies are being explored that aim to disrupt the genetic alterations driving these sarcomas, particularly on chromosome 12. Retroperitoneal sarcomas can cause bowel obstruction when large tumors compress the intestines.

1. CASE PRESENTATION. DEDIFFERENTIATED RETROPERITONEAL
LIPOSARCOMA, A RARE CAUSE OF BOWEL OBSTRUCTION
AUTHORS: Sinziana Ionescu1, Marian Marincas1, Octavia Luciana Madge2, Madalina Radu3,
Adina Ene3, Mihai Ceausu4, Mirela Gherghe5, Irinel Gabriel Dicu-Andreescu2, Silvia Mosoiu6 ,
Radu Valeriu Toma 7, Laurentiu Simion1
1. Bucharest Oncological Institute, General and Oncological Surgery Clinic I, “Carol Davila” University of Medicine and Pharmacy; 2.
Bucharest Oncological Institute, General and Oncological Surgery Clinic I; 3. Bucharest Oncological Institute, PathologY Department; 4.
Bucharest Oncological Institute, Pathology Department, “Carol Davila” University of Medicine and Pharmacy; 5. Bucharest Oncological
Institute, Department of Nuclear Medicine; 6. Bucharest Oncological Institute, Medical Oncology; 7. Bucharest Oncological Institute,
Radiotherapy1
Figure 5. Lipoblasts (left panel),
spindle cells (upper right panel),
myxoid area with curvilinear
vessels, HE, 10x Figure 6. Intense
diffuse immune response to p16 in
tumor cell nuclei (top left panel);
positive focal reaction to p53 in
tumor cell nuclei (top right panel);
Ki-67 positive in ~ 20% of tumor cell
nuclei (bottom left panel); CD34
positive in vessels, negative in
tumor cells (bottom right panel),
10x
Figures 1-4. Intraoperative aspects (tumor in situ, dissected tumor from
adherent planes, specimen) of retroperitoneum tumor (differentiated
liposarcoma)
Figure 1 Figure 2 Figure 3 Figure 4
Figure 5 Figure 6
Figure 7
Figure 7 a, b, c. Lumbar cross
sections at L4. A pre-operative
computer tomograph B-
Postoperative appearance of
computed tomography 4 months
after surgery C- Postoperative
aspect PET-CT 5 months after the
intervention B, C. No radiological
signs of recurrence or other
pathological aspects
The main subgroup of liposarcomas is represented by well-differentiated liposarcoma (WDL) / atypical
lipomatous tumor and dedifferentiated liposarcoma (DDL), which form a unitary histological and behavioural
spectrum. WDL and DDL are found mainly in middle-aged and elderly people, especially in the
retroperitoneum and extremities. WDL bears many similarities to mature adipose tissue, but has fibrous
septation and varying degrees of atypia and nuclear expansion. WDL does not spread, but can be
differentiated into DDL, which is associated with more aggressive clinical behaviour, a higher risk of local
recurrence, and the ability to spread. Although DDL has fewer metastases than other pleomorphic sarcomas,
its evolution is affected by its location, with retroperitoneal tumors having a much more severe prognosis
than those located in other locations. DDL is similar to undifferentiated pleomorphic or spindle cell sarcoma
and is usually a non-lipogenic sarcoma that develops with WDL, as a recurrence of WDL or as a new
pathological process. WDL and DDL have substantially similar genetic abnormalities; both are related to high-
level amplifications in the 12q13-15 chromosomal region, which contains the CDK4 and MDM2 cell cycle
oncogenes. DDL also contains additional genetic modifications, such as 6q23 and 1p32 co-amplification.
While surgical excision remains the therapy of choice for people with recurrent aggressive disease or
metastases, targeted innovative treatments targeting gene therapy on chromosome 12 are currently being
investigated. Retroperitoneal sarcomas are a rare cause of intestinal obstruction, especially in the context of
non-invasive retroperitoneal digestive organs, however, in some cases, the large volume of the tumor can
compress the intestinal loops.