P005 Signet Ring Cell Carcinoma Mimicking Crohn’s Disease
Authors: Anderson Colin , Taleban Sasha , Kim David , Stewart David , Gopireddy Dheeraj 
Published: December 2019

CASE:
A 77-year-old woman with history significant for microscopic colitis, essential thrombocythemia, and hypothyroidism initially presented in February 2019 with abdominal pain, intractable nausea and non-bloody, non-bilious vomiting over two months. Initial CT abdomen/pelvis showed multiple discontinuous foci of wall thickening and narrowing within distal small bowel including terminal ileum, with dilation of the proximal small bowel, concerning for Crohn’s disease (CD). After a similar presentation to the ED in March 2019, she had follow-up with the gastroenterology clinic in April 2019, which also revealed a 30 lb weight loss over previous 5 months. She was evaluated with an upper endoscopy, which was unrevealing with nondiagnostic duodenal biopsies. She was readmitted that month with similar complaints; labs were significant for fecal calprotectin 658 mcg/g, WBC 11.9 K/mm3, and CRP 6.8 mg/L. MR enterography showed small bowel obstruction from high grade stricture in TI favoring fibro-stenosing CD. A colonoscopy showed severely edematous ileal mucosa at the IC valve and the TI could not be intubated due to edema and stenosis. A presumed diagnosis of CD was made, and the patient was started on steroids and TPN, improved clinically, and was discharged. In June 2019, she was readmitted with an SBO, an MRI showed a high-grade fibrostenotic stricture in the TI, and patient underwent an ileocecectomy. Intraoperatively, she had a high-grade small intestinal obstruction with significant small intestine dilation. The appendix appeared normal. The findings were noted to be suspicious for Crohn’s disease. Pathology was consistent with adenocarcinoma, signet ring type arising from the appendix infiltrating bowel wall. Immunoreactive neuroendocrine markers were positive for synaptophysin and CD56.

CONCLUSION/DISCUSSION:
The first report of appendiceal adenocarcinoma was in 1887, and only a few hundred cases have been reported since then. Signet ring cell adenocarcinomas (SRCC) represent 4% of all appendiceal carcinomas (1), as the majority of SRCC originate from the stomach (63.4%) or colon (18.2) (2). Metastatic appendiceal adenocarcinoma has a 7% five-year survival rate, with signet cell type metastasizing in 76% of the cases (3) at time of diagnoses. Most reports regarding SRCC evolved from the stomach as primary tumor site with metastasis to the appendix. Only one other previous case of appendiceal SRCC with a similar presentation has been reported. (4) Appendiceal adenocarcinoma has been shown to have similar signs and symptoms as CD including recurrent bowel obstruction, abdominal pain and vomiting. Our patient was unique in that her clinical, imaging, and endoscopic findings mimicked CD, juxtaposed with other studies where either imaging or endoscopic findings were concerning for another diagnosis besides CD. Imaging may help distinguish between CD and appendiceal carcinoma but the differences can be extremely subtle (5, 6). Due to the aggressive nature of SRCC, early detection is critical. Our case further highlights the need for histologic confirmation of CD before ruling out other etiologies.