Case 216 - Discussion

Uploaded: 2008-05-08, Updated: 2008-05-09

EMA

Vimentin

CK5/6

CK19

CK8/18

CK14

CD99

CD99

CD34

EGFR

S100

P63

PAS-H

• IMMUNOHISTOCHEMISTRY

  • Positive:

    • CD99

    • Vimentin

  • Negative:

    • CK8/18

    • CK5/6

    • CK14

    • CK19

    • CD34

    • S-100

    • EMA

    • p63

    • EGFR

• ELECTRON MICROSCOPY

  • Ultrastructurally, prominent pools of cytoplasmic glycogen, rare primitive cell junctions and spars organelles are identified. The glycogen occurs principally as small and large focal deposits within the cytoplasm of the tumor cells. No osteoid is seen. No smooth muscle differentiation is seen.

• MICROSCOPIC DESCRIPTION

  • The tumor cells form sheets and nests in a background with an edematous stroma and prominent geographic necrosis. The tumor cells are small to moderate and oval to polygonal with minimal to small amount of cytoplasm.  The tumor cells are poorly differentiated with high nuclear-cytoplasmic ratios, although a vaguely epithelioid appearance is seen in some areas. The nuclei are irregular or round in some foci with hyperchromasia and occasionally prominent nucleoli. No rosette formation is present.

  • The immunoprofile is consistent with that of Ewings's sarcoma, with the negative cytokeratin staining making the diagnosis of adamantinoma and synovial sarcoma much less likely. The electron microscopic findings are likewise suggestive of Ewing's sarcoma.

• CYTOGENETIC STUDIES

  • The preliminary cytogenetic findings of t(1;10) however, has not been described in Ewing's sarcoma and is not a known fingerprint for any particular neoplasm.