PMC9487307_01
Histological findings of the tumor. Hematoxylin and eosin (HE) stain. The tumor centered in the submucosa with focal invasion to the mucosa. (A) A biphasic histology with epithelial and spindle cells was noted (B). Cytoplasmic eosinophilic granules and globules were observed in the bland-looking epithelial cell component (C). The spindle cells arranged in reticular (D) and storiform (E) pattern. The spindle cell component shows a bland appearance (F). The scale bars (2mm in A, 500mum in B and E, 200mum in D, 100mum in C and F).
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Histological examination showed a well-demarcated tumor centered in the submucosa with focal extension to the mucosa ( Figure 1A ) with ulcer formation. The tumor showed a biphasic morphology, consisting of relatively uniform epithelial cells and spindle cells ( Figure 1B ). Distinctive eosinophilic granules and globules were also observed in the cytoplasm ( Figure 1C ). The spindle cell component had hypocellular myxoid areas with a reticular growth pattern ( Figure 1D ) and hypercellular areas with fascicular and storiform growth patterns ( Figure 1E ). The spindle cells had pale eosinophilic cytoplasm and elongated or plump nuclei with or without small nucleoli ( Figure 1F ).
Immunohistochemical findings of the tumor. Both the epithelial and spindle cell components diffusely express Vimentin (A) and CD10 (B). The epithelial cells are strongly positive for CD56 (C) and S100 (D), and focally positive for EMA (E). The Ki-67 index was low (F). The scale bars (200mum in A-E, 100mum in F).
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By immunohistochemistry, both the epithelial and spindle cell components were diffusely positive for vimentin ( Figure 2A ), CD10 ( Figure 2B ) and bcl-2. The epithelial cells also strongly expressed CD56 ( Figure 2C ) and S100 ( Figure 2D ), and showed focal staining for EMA ( Figure 2E ), whereas the spindle cell component lacked expression of CD56, S100 and EMA ( Figures 2C-E ). The Ki-67 proliferative index was low (about 5%) ( Figure 2F ).
The detection of PTCH1::GLI2 fusion. (A) RNA-based NGS revealed a novel PTCH1::GLI2 fusion. (B) PTCH1::GLI2 fusion were confirmed by Sanger sequencing. (C) Schematic representation indicates PTCH1 (exon 1) ::GLI2(exon 8) fusion. Arrows indicate the direction of transcription for each gene. Exons and introns are represented by colored boxes and lines, respectively.
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It revealed a novel PTCH1(exon 1)::GLI2(exon 8) fusion, which was further confirmed by Sanger sequencing ( Figures 3A-C ).