Terminal Ileal Carcinoid Tumor in Active Crohnʼs Disease

Abstract

Purpose: Crohn's disease (CD) and carcinoid tumors commonly affect the terminal ileum (TI). Clinical, radiographic and pathologic findings in these conditions may be difficult to distinguish, and patients often undergo surgery for bowel obstruction before a diagnosis is confirmed. We report a case of coexisting CD and TI carcinoid tumor which highlights some of the diagnostic difficulties. Methods: Case Report: A 38 year old woman with a 10-yr history of CD ileocolitis presented for routine follow-up. She had been maintained in asymptomatic remission on 2.4 g/d Asacol for 4 years. Recent episodic epigastric pain, nausea and vomiting led to an ultrasound showing a 1.0 cm liver lesion. CT enterography showed a liver FNH, along with a focal nodular area of enhancement in the TI. Concern was raised for a carcinoid tumor, but ileocolonoscopy showed only TI ulceration. Biopsies showed mild active chronic ileitis. She returned for reimaging after 4 months of budesonide. While TI mucosal hyperenhancement improved, a 0.9 × 0.8 cm nodular area remained. A 24-hr urine collection for 5-HIAA was normal. Octreoscan showed activity at the 24-hr images in the anterior ileal wall, but 48-h images showed resolution of this uptake. This was thought to represent physiologic excretion of the tracer, and not be consistent with carcinoid. Results: Based on continued presence of the nodular mass with resolved TI inflammation following budesonide therapy, surgery was recommended for definitive diagnosis. She underwent laparoscopic-assisted right hemicolectomy with en-bloc lymphadenectomy. Histology showed a carcinoid tumor with invasion into the surrounding adipose tissue, along with 3 ulcerated strictures (min. diameter 3 mm), not present on radiographic imaging. Sixty regional lymph nodes were negative for tumor. Conclusion: Despite careful endoscopy with biopsy, CT scans, and nuclear imaging, the diagnosis of a carcinoid tumor in the background of CD was not made until surgical excision. CD and carcinoid can both coexist and mimic each other, with up to 2.3% of TI carcinoids being initially misdiagnosed as CD. Furthermore, an incidental carcinoid diagnosis is made in 3.6% of CD resections. Most cases require surgical intervention for diagnosis, as in our case. An unexpected finding was significant ileal stricturing disease, which was not appreciated on CT enterography. Due to symptomatic, radiographic, and even histologic similarities between CD and carcinoid, accurate diagnosis remains challenging. Clinical suspicion for these diagnoses should remain high when the clinical picture remains unclear.