Primary retroperitoneal sarcomas represent a diverse,
of which liposarcoma is the most common,
1,2,3,4,5 representing approximately 35% of malignant retroperitoneal tumors in adults.
Liposarcoma is defined as a malignant retroperitoneal primary tumor derived from various elements of the primitive mesenchyme,
and embryonic remnants that may originate in any region that contains fatty tissue.1,2,3,5,6
The symptoms are related to the location and size of the tumor depending on the structures underlying it.
The usual age of presentation is between 50 and 70 years of age,
except for myxoid liposarcoma that occurs in younger patients.
There is a slight predilection for the male gender.1,2,3,4,5
Macroscopic features: Smooth,
yellow in color,
can grow up to 20 cm and often affects the kidney or adjacent organs.
Microscopic features: Tumor with adipose phenotype with characteristic vascularity and loose stroma.
Immunohistochemistry: Immunostains for liposarcomas include CD34,
S-100 protein and desmin.1,4
In computed tomography (CT),
the lesions show a degree of fat loss,
with Hounsfield units ranging from -10 to -100; the tumor has a slightly higher attenuation than normal retroperitoneal fat.
Main patterns by tomography according to the amount and distribution of fat in the tumor:
- Focal fatty areas <-20 HU; other foci of soft tissue attenuation> 20 UH.
- Solid pattern: attenuation values> 20 HU (mainly myxoid tissue).
- Pseudo-cystic pattern: homogeneous density between> 20 and <20UH.
In magnetic resonance imaging (MRI),
liposarcomas are usually hypertensive in T1,
hyper to isointense in T2 and hypointense with fat suppression technique.
If fat is visible,
this method tends to be the most sensitive modality.
Preoperative biopsy is often not necessary.
The treatment of choice is complete surgical resection with free margins of the tumor with resection of the adherent structures.
The use of radiotherapy and chemotherapy is controversial.
Radiotherapy improves disease-free survival in high-grade lesions.
Chemotherapy is not indicated for low-grade sarcomas and its use for high-grade sarcomas is controversial.1,5