PMC10293602_01
Case 1) a. MRI leg showing hyperintense lesion on T2WI, b. The vague nodular proliferation of spindle cells, H&E x100, c. Plump spindle cells with a vesicular nucleus, H&E x400, d. CD68, x100, Inset: Desmin, x100, e. Ki67, x100, f. FISH for EWSR1 showing break-apart red and green signals
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F1
MRI features were suggestive of a peripheral nerve sheath tumor (Figure 1a). Multiple sections examined from the lesion showed a well-circumscribed encapsulated neoplasm composed of oval to spindle-shaped cells arranged in fascicles, sheets, and storiform pattern with peripheral lymphoid cuffing (Figure 1b). The cells exhibited moderate nuclear pleomorphism with vesicular nuclear chromatin (Figure 1c). They were negative for desmin (Figure1d, inset), S100, Smooth Muscle Actin (SMA), Pancytokeratin (PanCK), CD45, ERG, CD99, CD34 and ALK. The ki67 index was 10% (Figure 1e). Fluorescence in situ Hybridisation (FISH) was positive for EWSR1 rearrangement by using a DNA break-apart probe (CytoTest Inc.) at chromosome band 22q12.2 (Figure 1f).
PMC10293602_02
Case 2) a. H&E x100, b. spindled to ovoid cells, H&E x400, c. CD68, x100, d. Ki67, x100
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F2
Occasional atypical cells were noted (Figure 2a, b). Patchy immunoreactivity of neoplastic cells was noted for CD68 (Figure 2c), EMA, desmin, CD99, and BCL2. Ki67 proliferative index was 10-12% (Figure 2d).
PMC10293602_03
Case 3) a. shows spindle cell proliferation with a peripheral rim of lymphoid cells, H&E x100, b. plump spindled to ovoid cells, H&E x400, c. CD68, x100, d. Ki67, x100, Inset: Desmin, x100
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F3
There was a dense chronic inflammatory cell infiltrate comprising lymphocytes and histiocytes at the periphery of the tumor (Figure 3a, b). On IHC, the neoplastic cells were focally positive for CD68 (Figure 3c), EMA, and SMA. They were negative for PanCK, desmin (Figure 3d inset), CD45, CD34, S100, H - caldesmon, HMB45, synaptophysin, CD21, CD23, MPO, CD1a, BCL2, CD30 and ALK. The ki67 index was 12% (Figure 3d).