case_images: PMC8248363_01
case_images: Fecal calprotectin dosage trend and infliximab administrations.
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case_images: The laboratory tests found a remarkable increase of fecal calprotectin in recurrent determinations and variable decrease after infliximab injections ( Figure 1 ).
case_images: Collagenous colitis pattern. The pink band is seen beneath the surface epithelium and the lamina propria contains increased chronic inflammation (A). Masson trichrome stain highlights the irregularly expanded subepithelial collagen thickening. Note the entrapped inflammatory cells and small vessels (B). CD3 immunostain. The CD3 immunostain confirms that the lymphocytes CD3+ T-cells are predominantly in the lamina propria and are increased (C).
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case_images: Figure 2 ). From June 2019 to
case_images: Basal abdominal CT scans at the onset symptoms of pan-colitis with diffuse thickening of the colon walls (A). Improvement of pan-colitis after 8 months of infliximab treatment and 9 months of Pembrolizumab discontinuation (B). Persistent mild colitis after 24 months of Pembrolizumab discontinuation (C).
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case_images: f3
case_images: The instrumental follow-up with CT scan achieved in January 2021, 24 months after the latest administration of pembolizumab (carried out on January 2019), showed a persistent and remarkable stability of oncological disease in lung, lymph-nodes, and bone, despite the widespread inflammation of the colon in toto described as bowel wall thickening and colonic distension ( Figure 3 ).
case_images: Trend over time of the radiological response to pembrolizumab by RECIST Criteria version 1.0 and grade of gastrointestinal irAE (diarrhea) by CTCAE version 4.0 *Hospitalization; PD, Partial Response (according to RECIST v1.0); PEMBRO, pembrolizumab.
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case_images: f4
case_images: The trend over time of the radiological response to immunotherapy and gastrointestinal toxicity evolution is shown in  Figure 4 .