Surgical Pathology Criteria

Myxofibrosarcoma

Differential Diagnosis

 

Myxofibrosarcoma Low Grade Fibromyxoid Sarcoma
Pleomorphic nuclei present At most, focal moderate pleomorphism, but usually minimal or absent
May be cellular Overall paucicellular
May have increased mitotic activity Few mitotic figures
Abnormal mitotic fibures may be present No abnormal mitotic figures
Lacks alternating fibrous and myxoid areas Features alternating fibrous and myxoid areas
Often subcutaneous Usually deep soft tissues

 

Myxofibrosarcoma High Grade Pleomorphic Sarcoma (MFH)
Prominent myxoid stroma Lacks myxoid stroma
Curvilinear vascular pattern No organized vascular pattern

 

Myxofibrosarcoma Aggressive angiomyxoma
Large cytologically atypical cells Small bland cells
May have frequent mitotic figures Rare mitotic figures

 

Myxoid Liposarcoma Myxofibrosarcoma
Lipoblasts frequent No lipoblasts
Vacuoles in lipoblasts are clear Vacuoles, if present, contain material similar to adjacent myxoid stroma
Lacks pleomorphic cells At least focally pleomorphic
Rare in subcutis Frequent in subcutis
t(12;16) or t(12;22) No consistent abnormalities

 

Myxofibrosarcoma Intramuscular Myxoma and Juxta-articular Myxoma
Pleomorphism present Uniformly small bland cells
More cellular Extremely paucicellular
Mitotic figures may be present Mitotic figures practically never present
Arching vessels Markedly hypovascular

 

Myxofibrosarcoma Cellular Myxoma
Pleomorphism present Uniformly small bland cells
Mitotic figures may be present Mitotic figures rare
May have perivascular increase in cellularity No perivascular increase in cellularity

 

Fibromatosis, Abdominal Desmoid, Extra-abdominal Desmoid, Mesenteric, Retroperitoneal and Pelvic Myxofibrosarcoma
No pleomorphism Cytologic pleomorphism present
Usually dense stroma but focally may be myxoid No dense stroma
Vessels lack arching pattern Arching vessels

 

Myxofibrosarcoma Inflammatory Myxohyaline Tumor of Distal Extremities
Rare in distal extremities Distal extremities
May have frequent mitotic figures Infrequent mitotic figures
Infrequent inflammation Prominent inflammation

 

Myxoid DFSP Myxofibrosarcoma
No cytologic atypia or pleomorphism Atypical, pleomorphic nuclei
CD34 positive, nearly all cases Negative
No arcuate vascular pattern Arcuate vascular pattern

 

Myxofibrosarcoma Ischemic Fasciitis
Cytologically atypical to malignant No clear cytologic malignancy
Frequent atypical mitotic figures Atypical mitotic figures rare
Fat necrosis and fibrin rare Fat necrosis and fibrin characteristic
CD34 negative May be CD34 positive

 

Myxofibrosarcoma Giant Cell Fibroblastoma
Usually seen in adults, rare under 20 Mean age 3-6 years
Cytologically atypical but no multinucleated giant cells Giant cells appear multinucleated rather than cytologically atypical
May be mitotically active Mitotic figures rare
Lacks pseudovascular spaces Pseudovascular spaces present

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