Liposarcomas (LPS) is the most common malignant mesenchymal neoplasms,
accounting for approximately 20% of all sarcomas.
Malignant adipocytic tumors are a heterogeneous group of lesions,
with morphologically and genetically distinctive features.
This biologic diversity is associated with remarkable clinical heterogeneity,
ranging from neoplasms of intermediate biologic potential incapable of systemic spread to aggressive sarcomas with a significant potential for metastasis.
LPS are also the most common primary retroperitoneal malignant neoplasms,
representing 33% of all retroperitoneal sarcomas.
Retroperitoneal liposarcomas (RPLPS) usually occur in middle-aged adults in the 5th and 6th decades of life but have been described at all ages (2-98 years).
The distribution is supposedly equal,
but some studies suggest that they are a little more frequent in females. As they are slowly growing tumors and the RP is a deep expandable soft tissue space,
they usually do not cause signs or symptoms unless they have an important size.
They can produce increased abdominal girth,
palpable lump,
or symptoms secondary to compression of local structures (gastrointestinal,
urologic,
or neurological).
They generally tend to measure > 5 cm or 10 cm at presentation.
Diagnosis and treatment require a multidisciplinary approach in specialized centers.
Surgical resection combined with resection of other adjacent organs is usually necessary.
Complete surgical removal may be difficult and recurrence is very common.
Radiologists play a primary role in assessing the extent of the primary tumor,
evaluating postsurgical resection changes and performing follow-up studies to detect recurrences as early as possible.
The World Health Organization (WHO) revised the Classification of Tumours of Soft Tissue and Bone in 2013.
Some of the terms used previously like “round cell liposarcoma” and “mixed-type liposarcoma” were deleted.
With these changes,
current classification,
based on increasing order of aggressiveness,
stays as follows of:
Table 1
Taking into account their pathologic description Atypical Lipomatous Tumor (ALT) and Well-Differentiated Liposarcoma (WDLPS) are synonyms.
ALT is most frequently referred for tumors of the limbs and subcutaneous tissues with a high likelihood of curative resection.
Whereas resections of tumors arising in deep tissues of the trunk,
commonly referred to as WDLPS,
are rarely curative.
Locally aggressive WDLPS account for the majority of cases followed by dedifferentiated liposarcoma.
Myxoid and pleomorphic subtypes are very uncommon.
The most common staging system used for predicting the systemic outcomes of RPS is the UICC/AJCC-8 cancer stating system for the prognostic classification of sarcomas revised in 2017.
Table 2
References: © AJCC Cancer Staging Manual, Eight Edition (2017) published by Springer International Publishing.