Table 5 Pathological characteristics of the 13 unclassifiable cases with positive EWSR1 rearrangement on FISH
Case no. | Age/sex/site | Pathology |
|---|---|---|
1 | 33/M/shoulder | Fascicular spindle to focally more polygonal cell tumour; moderate to marked atypia. Extensive necrosis and mitoses. CD34+ in most cells; focal nuclear S100 protein+, very focal AE1/AE3, CD99 and EMA Final interpretation: ‘Sarcoma NOS’ |
2 | 47/F/foot | Multinodular spindle and polygonal cell tumour. Focal rhabdoid features and hemangiopericytic pattern. bcl-2, INI1 and focally CD99+, very focal S100 protein+ Final interpretation: ‘Findings not conclusive. Spindle cell sarcoma NOS; possible myoepithelial tumour, MPNST or extraskeletal myxoid chondrosarcoma’ |
3 | 52/M/shoulder | Small ovoid cells separated by fibrous septa. Largely solid; focal myxoid change. Focal necrosis and prominent mitoses. Focal EMA; all other markers negative. Features inconclusive for myoepithelial carcinoma. Some areas resembling EMC Final interpretation: ‘Malignant neoplasm, unclassifiable’ |
4 | 56/M/shoulder | Spindle and ovoid cell neoplasm, focal myxoid change, microcyst formation. Focal CD34, bcl-2 and CD99+ Final interpretation: ‘Findings not conclusive. Some MLPS-like features. Possibly solitary fibrous tumour’ |
5 | 11/M/subcutis of forearm | Moderately circumscribed lesion of plump ovoid and spindle cells with elongated cytoplasmic processes in myxoid stroma. No significant pleomorphism or necrosis. EMA, INI1 and focal D2-40+; claudin-1, cytokeratin and CD34− Final interpretation: Features resembling epithelioid perineurioma but immunophenotype not wholly supportive. Possible EMC |
6 | 54/M/kidney | Fascicular spindle cell tumour; moderate atypia; focal necrosis and prominent mitoses. Focal nuclear S100 protein, AE1/AE3, CD99, CD56 and CD34+ Final interpretation: ‘High-grade spindle cell sarcoma’ |
7 | 27/M/oropharynx | Epithelioid cells with mild atypia in nests in hyalinised or basement membrane-like stroma; basaloid cells also present. Diffuse strong MNF116, EMA, CK5/6, CK14 and p63+. CD10 and calponin+in peripheral cells Final interpretation: ‘Probable myoepithelial neoplasm without identifiable partner gene’ |
8 | 57/F/neck | Small to medium-sized epithelioid and polygonal cells with spindle cell areas. Up to one mitotic figure in 50 high power fields. Possible foci of adipocytes. Diffuse nuclear S100 protein and p16+; focal desmin and GFAP+. INI1+ Final interpretation: ‘Borderline tumour which cannot be conclusively characterised’ |
9 | 69/M/thyroid | Polygonal and spindle cell neoplasm. Focal variable FLI1, INI1, TLE1, CD56, CD99 and bcl-2+ Final interpretation: ‘Polygonal and spindle cell tumour of indeterminate (probably mesenchymal) lineage, but not otherwise classifiable. Does not fit into any specific class of EWSR1-rearranged neoplasm’ |
10 | 82/M/neck | Focally necrotic polygonal cell tumour. S100 protein, synaptophysin and weak focal EMA and chromogranin+ No detectable EWSR1-CREB1 or EWSR1-ATF1 fusions with RT–PCR. No BRAF mutation detected |
11 | 64/F/not available | Focally infiltrative biphasic neoplasm with bland spindle cells and epithelioid component, with occasional mitoses but no necrosis. Epithelioid component positive for CK7 and EMA Final interpretation: ‘Possible myoepithelial neoplasm’ |
12 | 34/M/spinal cord | Infiltrative tumour composed of ovoid cells in irregular cords within fibrous tissue. Focally EMA+, S100 protein, STAT6 and MUC4− Final interpretation: ‘Benign mesenchymal neoplasm of uncertain lineage. Possibly myoepithelial tumour but immunophenotype incomplete’ |
13 | 60/F/thigh | Myxoid spindle cell tumour; prominent myxoid stroma. Areas of adipocytic differentiation (but morphology not in keeping with myxoid liposarcoma). Occasional mitotic figures; no necrosis. Diffuse S100 protein and p16+; weak focal CDK4+. No DDIT3 rearrangement with FISH Final interpretation: ‘Myxoid spindle cell sarcoma with adipocytic differentiation’ |
