Table 3 Morphology of SEF
Typical features | |
Macroscopy | Large, homogeneously white or white–tan, lobulated, and hard tumors |
Cell size and shape | Small to medium-sized plump to epithelioid cells |
Cytoplasm | Scant clear or eosinophilic cytoplasm |
Nuclei | Oval to slightly elongate angulated nuclei with finely speckled chromatin |
Cellularity | Variable within the neoplasm |
Atypia | Mild |
Matrix | Densely sclerotic, areas of metaplastic bone in some |
Pattern of cellular arrangement | Small clusters, nests and anastomosing cords |
Hybrid morphology | Areas of LGFMS or nodules of collagen reminiscent of HSCTGR in some |
Immunohistochemistry | MUC4 ++, EMA +/−, CD99 +/−, bcl2 +/−, pan-keratin -, S100/HMB45/MelanA - |
FISH | EWSR1 (or rarely FUS) rearrangements |
Previously unrecognized features in renal SEF | |
Current case 1 | A lobular or micronodular architecture due to neoplastic cells surrounding entrapped renal tubules in a concentric fashion |
Zonation in the neoplastic lobules around tubules with inner hypocellular and outer hypercellular appearance | |
Current case 2 | Exuberant epithelial hyperplasia and small gland budding in the entrapped native renal tubules, mimicking MEST |
High grade cytologic atypia | |