case_images: PMC9910764_01
case_images: MRI of the brain T2 FLAIR showing hyperintensity in the right lateral frontal lobe during early diagnostic workup (1) and later in the disease course after treatment (2). Treatments included IVIg, plasmapheresis, and rituximab.. FLAIR - fluid-attenuated inversion recovery; IVIg - intravenous immunoglobulin
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case_images: FIG1
case_images: Magnetic resonance imaging (MRI) of the brain was unremarkable except for a small area of hyperintensity in the T2 and fluid-attenuated inversion recovery (FLAIR) in the right lateral frontal lobe (Figure 1). A repeat MRI of the brain later in the course did show improvement in the hyperintensity in the right lateral frontal lobe, thought to be a sign of a positive response to therapies (Figure 1).
case_images: PET scan (1) and anteroposterior CT of the abdomen and pelvis (2) showing inflammation and increased uptake in the duodenum
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case_images: FIG2
case_images: A positron emission tomography (PET) scan showed increased uptake in the duodenal region, which correlated with a thickening of the duodenum seen on a CT of the abdomen and pelvis earlier in her hospital course (Figure 2).
case_images: Synaptophysin immunostaining (1) and H&E immunostaining (2). Images courtesy of Michael Naski.
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case_images: FIG3
case_images: Biopsy showed poorly differentiated NEC, with positive synaptophysin, overexpression of p53, strong positivity with the Ki-67 proliferation marker in more than 90% of the neoplastic cells, and CDX2 suggesting a gastrointestinal origin (Figure 3).
case_images: Anteroposterior CT of the abdomen and pelvis after five weeks of chemotherapy sessions
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case_images: FIG4
case_images: Despite the administration of chemotherapy over the next two months, repeat CT scans and endoscopy did not show improvement in the patient's ulceration (Figure 4).
case_images: Images from post-chemotherapy endoscopy of gastric antrum and cardia.  Images courtesy of Kenneth Lown.
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case_images: FIG5
case_images: A continuing infiltrative mass in the duodenal bulb was appreciated on repeat endoscopy, with a noted deep circumferential ulceration with active oozing of blood (Figures 5-6).
case_images: Further images from post-chemotherapy endoscopy, with re-demonstration of duodenal ulcerated mass. Images courtesy of Kenneth Lown.
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case_images: FIG6
case_images: A continuing infiltrative mass in the duodenal bulb was appreciated on repeat endoscopy, with a noted deep circumferential ulceration with active oozing of blood (Figures 5-6).