5 Non-neoplastic Lesions

Case 5.1 Ulcerative Colitis

The large section in Figure 5.1 demonstrates the typical morphological appearance of ulcerative colitis. The main pathological changes in this disease are restricted to the mucosa. The submucosa shows only signs of edema; larger numbers of inflammatory cells are not seen. The lamina muscularis propria is intact. In the schematic image (Fig. 5.1d), the mucosa is indicated with a red arrowhead, the submucosa with a yellow one and the lamina muscularis propria with a green one. Figure 5.1a represents a low-power magnification of the bowel wall, including all the indicated layers, in the area of the yellow rectangle in the schematic image. The magnified detail in Figure 5.1b demonstrates the edematous submucosa, which is free of inflammatory cells. The distortion of the crypts is also well seen. Figure 5.1c is a detail from the mucosa, illustrating intensive active inflammation with a collection of granulocytes in the lumen of a distorted gland (so-called cryptal abscess). Several lymph nodes are also present in the specimen (marked with the green arrows in the schematic image, Fig. 5.1d).

Fig. 5.1a

Fig. 5.1b

Fig. 5.1c

Practical points

• Inclusion of an entire transection of the intestine in a single large histologic section is advantageous not only with respect to tumor pathology, but also when assessing the extent and distribution of inflammatory lesions.
  
• Inflammation mostly restricted to the mucosa is typical of ulcerative colitis.

Fig. 5.1 Large-section histology image of ulcerative colitis.

Fig. 5.1d Schematic guide to the morphologic details in the large section in Fig. 5.1.

Case 5.2 Crohn’s Disease

Although somewhat tangentially sectioned, the large histologic section in Figure 5.2 reliably demonstrates the hallmark of Crohn’s disease: transmural inflammation leading to thickening of the intestinal wall. Figure 5.2a represents a low-power magnification of the area corresponding to the yellow rectangle in the schematic image (Fig. 5.2d) and illustrates the presence of inflammatory changes in all layers of the intestinal wall. Deep mucosal ulcerations are seen as well as the lymphoid follicles in the submucosa and subserosa. The submucosa is edematous, thickened (as indicated with the blue double-arrow in the schematic image) and contains inflammatory cells. A deep ulceration with incipient fissure formation is demonstrated in Figure 5.2b (corresponding to the area of the red rectangle in Fig. 5.2d). Comparison with the previous large-section image (Case 5.1) clearly shows the differences between ulcerative colitis and Crohn’s disease. As a hallmark of Crohn’s disease, epithelioid granulomas were found in the intestinal wall and in the lymph nodes. A lymph node containing granulomas (indicated with the blue arrow in the schematic image) is microscopically magnified in Figure 5.2c.

Fig. 5.2a

Fig. 5.2b

Fig. 5.2c

Practical points

• Transmural inflammation, the hallmark of Crohn’s disease, even when only focal, is easily seen in large sections.

Fig. 5.2d Schematic guide to the details in the large section in Fig. 5.2.

Fig. 5.2 Large-section histology image of Crohn’s disease.

Case 5.3 Crohn’s Disease

This large histologic section in Figure 5.3 demonstrates another case of Crohn’s disease. Pseudopolyps, wide ulcerations, transmural inflammation, and a pericolic abscess are seen. The pseudopolyps are indicated with yellow arrows in the schematic image (Fig. 5.3e). The blue rectangle in the schematic image indicates a fissure, magnified microscopically in Figure 5.3a. Figure 5.3b illustrates a deep ulceration and part of a pseudopolyp (corresponding to the red-colored area in Fig. 5.3e). An undermining ulceration is present in the blue-colored area in the schematic image and is histologically magnified in Figure 5.3c. The pericolic abscess marked with a yellow rectangle in Figure 5.3s is seen magnified in Figure 5.3d. Compared to the previous case (Case 5.2), the present image illustrates a more advanced stage of Crohn’s disease.

Fig. 5.3a

Fig. 5.3b

Fig. 5.3c

Fig. 5.3d

Practical points

• Inclusion of an entire transection of the intestine into a single large histologic section is advantageous not only with respect to tumor pathology, but also when assessing the extent and distribution of inflammatory lesions.
  
• Large, non-fragmented histologic images assist in making the proper differential diagnosis of the subtypes of inflammatory bowel disease.

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