PMC5397295_01
Computed tomographic scan of the orbit (layer A and layer B) demonstrates a heterogeneous soft-tissue mass in the right lateral orbital wall area.
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There was no clear boundary between the mass and lateral rectus, and the neighboring orbital wall was destroyed (Figure 1). The mass displaced the right middle cerebral artery a little bit, and the boundary with the branch of right anterior cerebral artery was not very clear (Figure 1).
Magnetic resonance imaging of the orbit demonstrates a mass with mixed long T1 and long T2 signals in the right retrobulbar region outside the muscle cone: (A, B) T1-weighted and (C) T2-weighted image.
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T1 and long T2 signals in the right retrobulbar region outside the muscle cone. The right lateral orbital wall was destroyed, the lateral rectus was compressed, and the right temporal lobe was pushed backward with a clear boundary noted (Figure 2).
Histologic section of the monophasic synovial sarcoma. The tumor is mainly composed of spindled component which is characterized by elongated cells with ovoid pale-staining nuclei, inconspicuous nucleoli, and scanty cytoplasm (hematoxylin-eosin, original magnification x20 [A], x40 [B]).
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Tissue specimens obtained demonstrated monophasic SS with spindle-shaped mesenchymal cells (Figure 3).
Immunohistochemical stains of the monophasic synovial sarcoma. The tumor is positive for (A) vimentin, (B) CD99, (C) calponin, and (D) Bcl-2 and negative for (E) alpha-SMA, (F) MSA, (G) CD34, (H) S-100, (I) MPO, (J) EMA, (K) HBME-1, (L) PCK, and (M) CK7 (original magnification, x20). Antibodies were as follows: anti-vimentin, anti-CD99, anti-calponin, anti-Bcl-2, anti-alpha-SMA, anti-MSA, anti-CD34, anti-S-100, anti-MPO, anti-EMA, anti-HBME-1, anti-PCK, and anti-CK7. The species were all rabbit. alpha-SMA indicates alpha-smooth muscle actin; CK7, cytokeratin 7; EMA, epithelial membrane antigen; HBME-1, Hector Battifora mesothelial epitope-1; MPO, myeloperoxidase; MSA, muscle-specific actin; PCK, phosphoenolpyruvate carboxykinase.
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Immunohistochemical stains were positive for vimentin, CD99, calponin, and Bcl-2 and negative for alpha-smooth muscle actin (alpha-SMA), muscle-specific actin (MSA), CD34, S-100, myeloperoxidase (MPO), epithelial membrane antigen (EMA), Hector Battifora mesothelial epitope-1, phosphoenolpyruvate carboxykinase (PCK), and cytokeratin 7 (CK7) (Figure 4).