Liposarcoma

Alternative diagnostic terms
None

Common anatomical locations
Most frequently occurs in the deep soft tissue of proximal extremities (thigh and buttock) and trunk (back and shoulder). The retroperitoneum and the testicular area are also commonly involved.

Pathology comment
Benign 75% of the time; amplification of MDM2 and/or CDK4 is frequently present.

Source
Folpe AL, Sbaraglia M, Paolo Dei Tos A, Pedeutour F. Atypical lipomatous tumor/well-differentiated liposarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumorclassification.iarc.who.int/chapters/33.

For diagnosis or treatment
Any center listed in the Sarcoma Centers Directory »

Patient support
Any organization with an established program for patient triage, support, and education. See Patient Support Organizations »

Clinical trials
SARC Clinical Trials – None
Find other clinical studies registered on ClinicalTrials.gov

Alternative diagnostic terms
None

Common anatomical locations
Retroperitoneum

Pathology comment
MDM2 and CKD4 are amplified in most cases. DDLPS is an atypical, well-differentiated liposarcoma showing progressive malignant changes. 

Source
Folpe AL, Paolo Dei Tos A, Pedeutour F, Marino-Enriquez A. Dedifferentiated lipoSarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumorclassification.iarc.who.int/chapters/33

For diagnosis or treatment
Any center listed in the Sarcoma Centers Directory »

Patient advocacy
Any organization with an established program for patient triage, support, and education. See Patient Support Organizations »

Clinical trials
SARC041 – Advanced Dedifferentiated Liposarcoma (DDLS)
Find other clinical studies registered on ClinicalTrials.gov

Alternative diagnostic terms
None

Common anatomical locations
Deep soft tissues of the extremities, typically in the thighs.

Pathology comment
Translocations producing FUS-DDIT3 (common) or EWSR1-DDIT3 (rare) fusion transcripts are pathognomonic. Myxoid Liposarcoma is sometimes referred to as round cell liposarcoma, which contains a round cell component.

Source
Folpe AL, Thway K, Nielsen TO. Myxoid liposarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumorclassification.iarc.who.int/chapters/33

For diagnosis or treatment
Any center listed as a SARC Honor Roll member in the Sarcoma Centers Directory »

Patient advocacy
Any organization with an established program for patient triage, support, and education. See Patient Support Organizations »

Diagnostic-specific organizations:
Rossy Foundation
Sarcoma-Oma Foundation

Clinical trials
SARC Clinical Trials – None
Find other clinical studies registered on ClinicalTrials.gov

Alternative diagnostic terms
None

Common anatomical locations
Mediastinum

Pathology comment
Typical pathology shows mixed histological features that include both conventional myxoid liposarcoma and pleomorphic liposarcoma and lacks the gene fusions and amplifications for myxoid liposarcoma, atypical lipomatous tumor, and dedifferentiated liposarcoma (FUS/EWSR1-DDIT3 gene fusions and MDM2 amplifications).

Source
Folpe AL, Alaggio R, Creytens D. Myxoid pleomorphic lipoSarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33

For diagnosis or treatment
Any center listed in the Sarcoma Centers Directory »

Patient advocacy
Any organization with an established program for patient triage, support, and education. See Patient Support Organizations »

Clinical trials
SARC Clinical Trials – None
Find other clinical studies registered on ClinicalTrials.gov

Alternative diagnostic terms
None

Common anatomical locations
Extremities in two-thirds of cases and more common in the lower rather than upper extremities.

Pathology comment
No areas of atypical lipomatous tumor, well-differentiated liposarcoma, or other lines of differentiation present.

Source
Folpe AL, Pedeutour F, Montgomery EA. Pleomorphic liposarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33 d bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2025 Jan 1]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33

For diagnosis or treatment
Any center listed in the Sarcoma Centers Directory »

Patient advocacy
Any organization with an established program for patient triage, support, and education. See Patient Support Organizations »

Diagnostic-specific organizations:
Rossy Foundation
Sarcoma-Oma Foundation
Wendy Walk

Clinical trials
SARC Clinical Trials – None
Find other clinical studies registered on ClinicalTrials.gov

Alternative diagnostic terms
Hemosiderotic Fibrolipomatous Tumor
Lipofibromatosis-like Neural Tumor

Common anatomical locations
PHAT develops in subcutaneous tissue of the lower extremities, mainly in the ankle/foot. Most tumors present as superficial or deep tumors in the extremities or trunk.

Pathology comment
PHAT is characterized by clusters of ectatic vessels surrounded by pleomorphic, haemosiderin-laden cells with nuclear pseudoinclusions; very low to absent mitotic activity; peripheral component of HFLT often seen. NTRK rearranged spindle cell variants are emerging. Phosphaturic Mesenchymal Tumor is a related subtype. The tumors are most often characterized by a monomorphic spindle cell phenotype, variable stromal hyalinization, and infiltrative growth. This provisional category includes the recently described lipofibromatosis-like neural tumors and tumors that closely resemble peripheral nerve sheath tumors (PNSTs).

Source
Fletcher CDM, Agaimy A, Paolo Dei Tos A, Folpe AL. Pleomorphic hyalinizing angiectatic tumor. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2025 Jan 1]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumorclassification.iarc.who.int/chapters/33

For diagnosis or treatment
Any center listed in the Sarcoma Centers Directory »

Patient advocacy
Any organization with an established program for patient triage, support, and education. See Patient Support Organizations »

Clinical trials
SARC Clinical Trials – None
Find other clinical studies registered on ClinicalTrials.gov

Alternative diagnostic terms
Angiomyolipoma
Epithelioid Angiomyolipoma

Common anatomical locations
PEComas show a wide anatomical distribution.

Pathology comment
PEComas are characterized by epithelioid and/or spindle cells with granular eosinophilic to clear cytoplasm; nested, trabecular, or sheet-like architecture with frequent perivascular orientation; variable co-expression of melanocytic and smooth muscle markers.

Source
Fletcher CDM, Doyle LA, Hornick JL, Argani P. PEComa. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33

For diagnosis or treatment
Any center listed in the Sarcoma Centers Directory »

Patient advocacy
Any organization with an established program for patient triage, support, and education. See Patient Support Organizations »

Clinical trials
SARC Clinical Trials – None
Find other clinical studies registered on ClinicalTrials.gov

Alternative diagnostic terms
Intramuscular Myxoma
Parachordoma (not recommended)

Subtypes (Recommended by WHO)
Mixed tumor, malignant, NOS
Myoepithelial carcinoma

Common anatomical locations
75% of myoepithelial tumors of soft tissue arise in the lower or upper extremities limbs.

Pathology comment
Myoepithelioma, myoepithelial carcinoma, and mixed tumor are myoepithelial tumors of soft tissue – a group of uncommon neoplasms that share morphological, immunophenotypic, and genetic features with their counterparts in salivary gland and skin. Malignant myoepithelial tumors of soft tissue are designated myoepithelial carcinomas. Rearrangements of EWSR1, FUS, or PLAG1 (in mixed tumors) can be detected. EWSR1 FISH alone may not be sufficient for distinguishing myoepithelial neoplasms from other tumors with EWSR1 fusions.

Note: High fluid content in MRI appearance of benign Myxoma has a pseudomalignant appearance. Other benign subtypes include Juxta-articular Myxoma, Aggressive Angiomyxoma, Atypical FibroXanthoma, Ossifying Fibromyxoid Tumor, Angiomatoid Fibrous Histiocytoma.

Source
Fletcher CDM, Jo VY, Hornick JL, Antonescu CR, Patel RM. Myoepithelioma, myoepithelial carcinoma, and mixed tumor. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2025 Jan 1]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33Benign 

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Patient advocacy
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Clinical trials
SARC Clinical Trials – None
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These are benign or atypical lipomatous that can occur in any age group (including children) and, as a general rule, do not represent malignant fatty tumors but can represent large, infiltrating tumors with a risk of local recurrence.

Alternative diagnostic terms
None

Common anatomical locations
None

Pathology comment
None

Source
None