PMC10247287_01
Gross view of the abdominal cavity overture depicts the exposed small bowel loops that are visibly filled with air due to CPR maneuvers. The presence of hemoperitoneum on the lower abdomen can be noted, filling the cavity. Additionally, we can observe the area of chronic damage on a non-perforated bowel loop with loss of serosa and exposure of inner layers. This image clearly depicts of the extent of abdominal pathology and highlights the damage sustained in both acute and chronic settings.
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A small bowel loop was observed to be severely damaged without macroscopic perforation (Figure 1).
Gross view of the 20cm section of the affected bowel loop, with two images for comparison. On the left, a non-fixated picture clearly shows the retraction and bleeding. A formalin fixated picture after a mid-section cut is displayed on the right. Notably, the image on the right reveals the replacement of mesenteric adipose tissue with pearly-white tissue, engorging enlarged regional lymph nodes, the rectification of vasculature, and contact with the bowel wall. These enlarged regional lymph nodes have a yellowish appearance with a darker center. Scale bar= 10 cm.
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Microphotographs of the junction between the mesentery and bowel wall. A  - at low magnification power shows the lesion's sclerosing nature with the fibroblast substitution of adipose tissue and rectification of vasculature. This lesion contacts the bowel wall in the upper-mid left field (H&E, 20X); B  - Lower image at a higher magnification power appreciating an admixture of fibroblasts engorging adipose tissue, with focal areas of fat necrosis and rectified vasculature (H&E, 100X); C  - Masson's trichrome staining in the same region as depicted in B. This image highlights the presence of variable-sized collagen bundles, which appear to be increased in number, interspersed, and engorging the surrounding adipose tissue (MT, 100X).
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The fibroblasts exhibited fine chromatin without evident nucleoli, pale eosinophilic cytoplasm, and no atypia or atypical mitosis (Figure 3).
Microphotograph of a 1.5cm mesenteric distant mass that exhibits the same features as the primary lesion but on a smaller scale. Notably, the image showcases the admixture of fibroblasts with adipose tissue in the bottom left and bottom right fields. In the middle of the image, a tangential cut of the bowel wall is visible, with the mucosa positioned on top (H&E, 20X); B  - Higher magnification power at the bottom right field of A. Masson's trichrome staining emphasizing the heterogeneous distribution of collagen bundles, varying in size, which exhibit an increased density and are intermingled within the adipose tissue. Additionally, focal areas of hemorrhage can be discerned (MT 40X).
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Microphotographs illustrating immunohistochemical staining for caldesmon (A), desmin (B), and smooth muscle actin (SMA) (C). The three images display a positive internal control on the left side, representing the muscularis propria of the bowel wall. In the center of each image, fibroblasts are observed, exhibiting either faint or focal staining positivity for these markers in comparison to the internal control. Multiple stains were employed to verify the positivity and intensity of these immunohistochemical stains (A, B and C - caldesmon, desmin, SMA 100X, respectively).
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An immunohistochemistry panel was performed to test for desmin, smooth muscle actin (SMA), caldesmon, beta-catenin, CD-117, DOG-1, S100, Sox-10, CD34, STAT6, IgG4, p53, NTRK, and Ki67 (Figure 5).