Table 3.
Summary of differential diagnoses of low-grade fibromyxoid sarcoma
| Tumor | Key histologic features | Immunohistochemistry | Most common genetic aberrations | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| MUC4 | Cytokeratin | SMA | beta-catenin | STAT6 | CD34 | S100 | EMA | |||
| Low-grade fibromyxoid sarcoma |
Alternating fibrous and myxoid areas Whorled growth pattern Bland to mildly atypical cells Arcades of small vessels Giant collagen rosettes (30%) |
+ | − | − | − | − | − | − | ± | FUS- CREBB3L2 fusion |
| Spindle cell squamous cell carcinoma |
Cytologic atypia and nuclear pleomorphism Surface squamous dysplasia |
− | + | − | − | − | − | − | + | |
| Desmoid fibromatosis |
Long sweeping fascicles of bland spindle cells Infiltrative growth pattern Large thin walled gaping blood vessels with perivascular edema |
− | − | + | + | − | − | − | − | CTNNB1 mutation |
| Solitary Fibrous Tumor |
Patternless arrangement of spindled to ovoid cells Variably collagenous stroma Prominent branching and hyalinized staghorn-shaped blood vessels |
− | − | − | − | + | + | − | − | NAB2- STAT6 fusion |
| Dermatofibrosarcoma protuberans |
Dermal based Uniform spindle cells arranged in storiform pattern Prominent infiltration of subcutaneous fat |
− | − | ± | − | − | + | − | − | COL1A1-PDGFB fusion |
| Neurofibroma |
Haphazardly arranged bland spindle cells with wavy nuclei -Loose myxoid and collagenized stroma Associated perineurial cells, fibroblasts and mast cells |
− | − | − | − | − | + | + | + | Biallelic inactivation of NF1 |
| Soft tissue perineurioma |
Storiform or whorled growth pattern Slender spindle cells with elongated tapered nuclei and bipolar cytoplasmic processes Collagenous to focally myxoid stroma |
− | − | − | − | − | ± | − | + | Deletion of 22q12 and mutation of NF2 |
| Nodular fasciitis |
Loose arrangement of plump spindled cells Microcystic stromal changes Extravasated red blood cells No hyperchromasia or cytologic atypia |
− | − | + | − | − | − | − | − | USP6 rearrangement |