MR Enterography May Identify Histologic Subtypes

The objective of a recent study was to determine if there are findings on MR enterography that can help one differentiate between different histologic subtypes of small-bowel lymphoma.

The study has concluded that non-Hodgkin’s lymphoma (NHL) associated with celiac disease has a tendency to manifest as a single, long, smooth, continuous bowel segment, often with aneurysmal dilatation.

Participants/Methodology
This retrospective analysis was comprised of 10 patients with histologically confirmed primary small-bowel lymphoma. There were four men and six women ranging between 44 and 85 years of age. Histological confirmation was based on endoscopy, laparoscopy, or laparotomy and the three prognostic categories were low, intermediate, and high grade.

MR enterography was performed on a 1.5 Tesla system and utilizing a single protocol. Coronal and axial true fast imaging with steady-state precession (FISP) sequences were obtained. Intravenous contrast was not administered. Diluted polyethylene glycol was ingested over a 45-minute period before scanning. Two abdominal radiologists reviewed the images.

Results of the Study
Nineteen small-bowel segments were involved by NHL in these 10 patients. Six out of 10 patients had histologically confirmed celiac disease. Six of the patients had B-cell origin NHL and included low-grade NHL, such as follicular and mucosa-associated lymphoid tissue (MALT), intermediate- to high-grade follicular NHL, and high-grade NHL.

Four patients had T-cell origin; all of them had underlying celiac disease. Patients with celiac disease had the longest segments of small bowel wall thickening, averaging 24 cm. There was circumferential bowel wall involvement in at least one segment in all 10 patients. Smooth margins were found in all six patients with celiac disease and were not a feature in those without the disease.

A smooth serosal contour was found with both T-cell and B-cell NHL associated with celiac disease. Aneurysmal small-bowel loop dilatation was only found in those patients with celiac disease. There was one patient with celiac T-cell NHL who had luminal narrowing due to intermediate- to high-grade disease.

There was circumferential diffuse distribution and no preferential mesenteric or antimesenteric involvement in 8 of the 19 diseased segments, all of which were identified in patients with celiac disease. Mesenteric fat infiltration without discrete lymphadenopathy was only identified in patients with high-grade NHL.

No significant difference was seen in signal intensity between lesions in patients with and without celiac disease.

Reviewer’s Comments
These results are useful in that they demonstrate a few characteristics of small-bowel lymphoma on MR enterography that can help suggest a certain histologic subtype and whether there is underlying celiac disease. These findings would provide for a challenging initial imaging diagnosis.

However, as there are not likely to be any immediate clinical implications, management would still rely on the final diagnosis by histologic confirmation. One limitation of the study is its small simple size.

Author: John C. Sabatino, MD

Reference
Lohan DG, Alhajeri AN, et al. MR Enterography of Small-Bowel Lymphoma: Potential for Suggestion of a Histologic Subtype and the Presence of Underlying Celiac Disease. AJR; 2008; 190 (February): 287-293: