PMC8645372_01
Scanning magnification shows groups of endometriotic glands surrounded by light gray staining stroma that is pseudodecidualized due to progestin treatment. Adjacent is a focus of tubular structures and nests with a pseudoinfiltrative growth pattern (arrowheads) (a, 20x). At intermediate magnification cells form tubular structures and nests with angular pseudoinfiltrative shapes, some surrounded by slit-like spaces set in dense collagenous stroma. The endometriotic gland in the upper right corner is surrounded by pseudodecidualized stroma (b, 100x). High magnification reveals the pseudoinfiltrative growth pattern of tubular structures and nests. Cells have relatively scant eosinophilic cytoplasm and round to oval monotonous nuclei, with some nuclear overlap. Chromatin is finely distributed, and occasional small nucleoli are seen (c, d; 400x).
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fig1
The endometrial stroma appeared light gray due to pseudodecidual change caused by progestin treatment (Figure 1). Adjacent to the endometriotic glands was a 5 mm focus of tubular structures and nests with a pseudoinfiltrative growth pattern (Figure 1(a) arrowheads).
Immunohistochemical stains for the mesothelial markers calretinin (a) and WT-1 (b) are strongly positive. Cytokeratin 7 (c) and cytokeratin 5 (d) are also positive (all 40x). These immunostains highlight the pseudoinfiltrative architecture at low-magnification images.
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fig2
Immunohistochemical stains revealed the lesional cell to be positive for the mesothelial markers calretinin and WT-1 and also positive for cytokeratins 7 and 5 (Figure 2).