PMC9163338_01
Images of the tumor. Computed tomography showed a nodule on the lower right side of the parotid gland. (A) Coronal plane; (B) transverse plane.
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F1
The ultrasound of the neck showed a substantial lesion of the right parotid gland, and the CT examination displayed a small nodule below the parotid gland (Figures 1A,B), which was initially considered as a benign tumor or tumor-like lesion of the parotid gland.
Histology and immunohistochemistry of the tumor. (A) Immunohistochemical results showed Vimentin diffuse positive (+) (IHC staining, x100). (B) The tumor consisted of the mucous area and the fibrous area with inflammatory cell infiltration in the mucus-like area, and the various fusiform cells can be connected to each other to form a network structure (H&E staining, x100). (C) At the junction of the mucous area and the fiber area, inflammatory cell infiltration could be observed (H&E staining, x100). (D) The tumor can be infiltrated into the parotid tissue (H&E staining, x100). (E) Large malformed cells with large nucleoli can be noted (H&E staining, x200). (F) The "inclusion body" nucleolus resembling Reed-Sternberg cells has been recognized as one of the characteristics of mucinous inflammatory fibroblastic sarcoma (H&E staining, x200).
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F2
Moreover, visible in the mucus area were the pseudo-fat cells, spindle cells involving adipose tissue, whereas the phagocytic cells can also be seen in some areas (Figures 2B-F, 3).
Atypical microscopic features in MIFS. (A) Virus-like cells with abundant cytoplasm and nucleoli (arrows). (B) Large malformed cells with two enlarged nuclei shown by arrows; (C) R-S cell-like tumor cells with markedly large nucleoli (arrows).
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F3
Moreover, visible in the mucus area were the pseudo-fat cells, spindle cells involving adipose tissue, whereas the phagocytic cells can also be seen in some areas (Figures 2B-F, 3).
Immunohistochemical findings in MIFS. (A) The tumor spindle cells and malformed cells were strongly positive for CD10. (B) Infiltrated inflammatory cells were strongly positive for LCA. (C) The reactive histiocytes were positive for CD68. (D) Reactive histiocytes were positive for CD163. (E) The tumor cells were negative for D2-40. (F) The tumor cells expressed low-proliferative Ki-67 (about 10%).
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F4