Myxofibrosarcoma
Differential Diagnosis
- Low grade myxofibrosarcoma
- Undifferentiated high grade pleomorphic sarcoma (MFH)
- Aggressive angiomyxoma
- Myxoid liposarcoma
- Intramuscular and juxta-articular myxoma
- Cellular myxoma
- Desmoid fibromatosis
- Inflammatory myxohyaline tumor of distal extremities
- Myxoid dermatofibrosarcoma protuberans
- Ischemic fasciitis
- Giant cell fibroblastoma
| 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 |
- Only high grade myxofibrosarcoma is in the differential diagnosis
- No clinical significance to distinction in high grade cases
| 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 |
