PMC10118902_01
Inflammatory fibroid polyp. (a, b) Low-power magnification showing a predominantly submucosal nodular proliferation with some extension into mucosa comprised of bland spindle-shaped mesenchymal cells, well-vascularized with concentric distribution of inflammatory infiltrate consisting mainly of eosinophils arranged around vessels. (c, d) High-power magnification showing bland spindle cells, small vessels, and eosinophil-rich mixed inflammatory infiltrate. (Hematoxylin and eosin stain: (a) original magnification x2; (b) original magnification x10; (c) original magnification x20; and (d) original magnification x60).
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fig1
Histologic sections showed a submucosal lesion with focal extension into the mucosa consisting of bland plump spindle cells embedded in a loose fibrous stroma and infiltrated by numerous eosinophils (Figure 1).
Immunohistochemical staining showed that the spindle-shaped mesenchymal cells were positive for vimentin (a) and negative for CD34 (b), CD117 (c), DOG1 (d), S-100 (e), SMA (f), STAT6 (g), and ALK (D5F3) (h) (original magnification: x20).
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fig2
Immunohistochemical (IHC) studies (Figure 2) showed that the spindle cells were positive for vimentin and negative for desmin, smooth muscle actin (SMA), S-100, CD117, DOG1, ALK (D5F3), Melan-A, HMB-45, CD34, and STAT6 indicative of fibroblastic lineage.