Terminal Ileitis Found Upon Imaging: Is It Always Crohn's Disease?

To the Editor: Terminal ileitis (TI), defi ned as infl ammation of the terminal ileum, is a common condition in clinical practice and is classically associated with Crohn ’ s disease (CD). However, a wide variety of diseases may be associated with ileitis ( 1,2 ). Diagnosis of the specifi c cause of ileitis is of paramount importance because misdiagnosis may result in critical delays or errors in patient management ( 3 – 5 ). Nonetheless, distinguishing between the various forms of ileitis remains a test of clinical acumen. Accurate diagnosis is suggested by a detailed history and physical examination, by laboratory testing, and by ileocolonoscopy and / or radiological evaluation. To study the diff erent entities associated with TI in clinical practice, we reviewed all patients with confi rmed imaging of TI on ultrasound admitted to our department over four consecutive years. An observational, descriptive, longitudinal study was performed, with a retrospective review of demographics, clinical presentation, laboratory data, treatment, and follow-up. Abdominal ultrasonography was performed in all patients and was complemented with computed tomography when necessary. Sonographic features compatible with TI included hypoechogenic mural thickening of the terminal ileum and hypoechoic enlarged mesenteric lymph nodes ( 6 ). Th e diagnosis of ileal CD was based on clinical, endoscopic, and histopathological data. Acid-fast bacilli smear and culture were performed in ileal biopsy specimens. An infectious etiology was presumed when there was clinical, analytical, and imaging remission aft er empirical antibiotic therapy, or when confi rmed by isolation of pathogenic microorganisms in stool cultures. Th is study assessed 62 patients with a median age of 38.2 years (18 – 82), with a slight predominance of females (56.4 % ). Th e main form of presentation was abdominal pain (93.5 % ) and diarrhea (67.7 % ). All patients presented with ultrasonographic features of TI, which were corroborated by computed tomography in 62.9 % . In this study, infectious etiology was confi rmed in 62.9 % ( n = 39) of patients, CD was diagnosed in 32.2 % ( n = 20), and ileum cancer in 4.9 % (ileal lymphoma — 2, adenocarcinoma — 1). Fecal pathogens were identifi ed in 7 patients: Campylobacter — 3, Yersinia — 2, and Salmonella — 2. No parasitic or tuberculosis infection was identifi ed. On comparing the groups with confi rmed CD and infectious ileitis, we found in the fi rst group higher median values of serum infl ammatory parameters (C-reactive protein: 9.8 vs. 7.4 mg / dl; leukocyte count: 16.650 vs. 11.170 / μ l), lower hemoglobin levels (10.45 vs. 13.5 g / dl, ttest, P =0.03), and a longer inpatient period (10 vs. 5 days). Patients diagnosed with CD maintain longterm follow-up in our outpatient clinic. In the current study, the diagnosis of CD of the ileum was confi rmed histopathologically in 32.2 % of patients with imaging of TI. We highlight that infl ammation of the terminal ileum is not always CD, and infectious etiology is a common cause (62.9 % in our study). Th e diff erential diagnosis of TI found on imaging, although sometimes diffi cult, is of critical importance to avoid further unnecessary diagnostic workup and inappropriate treatment.