case_images: PMC9256978_01
case_images: A regular hypoechoic mass on breast ultrasonography.
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case_images: An ultrasonography of the breast revealed a regular hypoechoic mass measuring 3.0 cm x 2.4 cm x2.8 cm in size and 4 cm distant from the nipple ( Figure 1 ).
case_images: Timeline.
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case_images: PMC9256978_01_fonc-12-878635-g002.jpg
case_images: f2
case_images: The timeline is shown in  Figure 2 .
case_images: Morphology and immunohistochemistry features of the synovial metaplasia and giant cell tumor of tendon sheath (A). Hemosiderin granule deposition in the lesion (B). Nest-like distribution of xanthomatous cells among monocytes (C). Immunoreactivity for Bcl-2 (D), SMA (E), and CD68 (F) in synovium-like cells, mononuclear cells, and osteoclast-like giant cells.
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case_images: These sheets of cells were composed of many rounded macrophage-like synovial cells and fibroblasts synovial cells and represented as synovial metaplasia ( Figure 3A ). Hemosiderin granules were distributed in the lesion ( Figure 3B ). The main part of tumor was blended with nested and scattered xanthomatous cells and osteoclast-like giant cells ( Figure 3C ). The immunohistochemical analysis revealed that the synovium-like monocytes and xanthomatous cells were positive for Bcl-2 ( Figure 3D ), SMA ( Figure 3E ), CD68 ( Figure 3F ), and CD10.
case_images: The absence of CSF1 (A) and USP6 (B) translocation in fluorescence in situ hybridization analysis.
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case_images: f4
case_images: In terms of fluorescence in situ hybridization (FISH) detection for the translocation of CSF1 gene and USP6 gene, the results were negative ( Figure 4 ).