PMC10134144_01
A 4/5 subtotal gastrectomy specimen showing the 12 x 4.5 cm fleshy mass with a pale-tan surface arising in the wall of the fundus.
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Grossly, the specimen contained a 12 x 4.5 cm well-circumscribed fleshy mass with a pale-tan surface on sectioning arising in the subserosa of the stomach (Figure 1).
Hematoxylin-eosin, original magnification x200. Low-power view of gastric follicular dendritic cell sarcoma with a well-defined subserosal tumor.
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Microscopic examination revealed a multi-lobated mass centered in subserosa of the fundic wall (Figure 2).
The tumor is composed of plump spindle cells arranged in fascicular, storiform, and whorling patterns with lymphocytic infiltrate in the background (x200).
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Tumor cells had plump eosinophilic cytoplasm with ill-defined cell borders generating a patternless diffuse growth, despite some places having short fascicles of spindle-shaped cells that produced a vague storiform pattern (Figure 3).
Tumor cells had hyperchromatic to vesicular nuclei and occasional prominent nucleoli. A few multinucleated tumor cells were also observed (x400).
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Focal nuclear pleomorphism were seen (Figure 4).
FDCS with sprinkling of lymphocytes in the tumor background with a perivascular cuff of lymphocytes (x400).
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In background, sprinkling of small reactive lymphocytes was noted and in certain spots, a perivascular cuff of lymphocytes was also detected (Figure 5).
Immunohistochemical staining showing cytoplasmic and membranous positivity for CD21 (a) and CD23 (b). C-kit (c) and CD34 (d) are negative.
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AE1/AE3, S100, CD34, CD30, HMB45, and EBER (Figure 6). A diagnosis of an extra-nodal gastric FDCS with metastasis to regional lymph nodes was rendered.