Intestinal and peritoneal lymphoma complicating Chron’s disease

Background Crohn’s disease is an inflammatory bowel disease which mostly affects the small intestine. It has a variable clinical course, with alternating attacks of exacerbation and remission. In the last decades, the incidence of Crohn’s disease has been increasing, so imaging of those cases has become more important. Case presentation We report a case of a male patient who was treated for Chron’s disease in the past three years and presented with abdominal pain. Post-contrast CT abdomen and pelvis was done revealing soft tissue thickening of intestinal walls in a skip fashion with multiple peritoneal deposits. The case was pathologically proven to be anaplastic large cell lymphoma on top of Chron’s disease. Conclusions The cause of the association between Crohn’s disease and lymphoma is still elucidated. Radiologists should be aware that Chron’s disease can be complicated by intestinal and peritoneal lymphoma and should suspect the presence of lymphoma on top of Chron’s disease if there is wall thickening of soft tissue attenuation affecting the small bowels in a skipping manner following the areas previously affected by Chron’s disease.


Background
Crohn's disease is an inflammatory bowel disease (IBD) which mostly affects the small intestine, especially the terminal ilium; however, it can affect any segment of the gastrointestinal tract from mouth to anal canal.It has a variable clinical course, with alternating attacks of exacerbation and remission.In the last decades, the incidence of Crohn's disease has been increasing, so imaging of those cases has become more important [1].

Case presentation
A 52-year-old male patient with a history of Crohn's disease for 3 years (proved by endoscopy and biopsy) on treatment, with a recent history of weight loss, night sweating and low-grade fever presented with abdominal pain and enlargement underwent abdominal US that revealed ascites, peritoneal masses and lymph nodes (LNs) referred for CT abdomen and pelvis (Fig. 1).
A post-contrast CT abdomen and pelvis was done using multidetector computed tomography (MDCT) enterography using a multidetector-row helical CT scanner (Toshiba Aquilion Prime 160 CT).A discontinuous marked circumferential minimally enhancing soft tissue mural thickening of the ileal loops with loss of identification of the normal three layers of the intestinal walls.The affected segments were separated by normal intestinal segments in between in a skip fashion.There were also multiple peritoneal masses implanted on the hepatic surface extending into the fissures as well as GB fossa with subsequent scalloping of liver surface, implanted on the right kidney surface with subsequent scalloping on *Correspondence: Rasha Karam rasha90karam@mans.edu.eg;rasha90karam@gmail.com 1 Diagnostic Radiology Department, Faculty of Medicine, Mansoura University, Elgomhoria St., Mansoura 35516, Egypt 2 Department of Radiology, Gastro-Intestinal Surgery Centre, Mansoura University, Elgomhoria St., Mansoura 35516, Egypt its surface and scattered in all pelvi-abdominal regions forming discrete and amalgamated masses (high peritoneal index).Multiple enlarged para-aortic, mesenteric LNs and mild ascites were present (Figs. 2 and 3).
Endoscopic guided biopsy from the thickened intestinal walls revealed anaplastic large cell lymphoma on top of Chron's disease.

Discussion
The cause of the association between Crohn's disease and lymphoma is still elucidated.Some studies reported that the development of lymphoma in Chron's patients is secondary to the use of immunosuppressive drugs which cause a drop in patient immunity [2].
The imaging characteristic of Crohn's disease is the skip lesions, meaning there are segments of normal mucosa between the affected segments [3].
Clinically, small bowel lymphoma has nonspecific symptoms like abdominal pain, nausea, vomiting and weight loss.The imaging findings of small bowel lymphoma include multifocal polypoid intestinal wall masses, homogeneously enhancing circumferential wall thickening with aneurysmal dilatation as lymphoma lacks desmoplastic reaction, with or without associated mesenteric lymphadenopathy [4].
Lymphoma can also affect the peritoneum giving imaging findings similar to those seen in peritoneal carcinomatosis including omental cakes and diffuse nodular peritoneal thickening [5].Radiologists should be aware that Chron's disease can be complicated by intestinal and peritoneal lymphoma and should suspect the presence of lymphoma on top of Chron's disease if there is soft tissue density with grey enhancement pattern within the thickened bowel wall with loss of normal triple layers of the bowel wall.The most interesting part about our case which according to our knowledge was not reported before is that the wall thickening seen in our case representing lymphomatous infiltration was found in a skipping manner following the areas primarily affected by Chron's disease (Figs. 2 and 3).

Conclusions
Intestinal lymphoma is one of the complications of Chron's disease, and when it affects the small bowel loops, it follows the segments primarily affected by Chron's disease and spares the normal segments in between in a skip manner.

Fig. 1 Fig. 2
Fig. 1 Lymphomatous intestinal affection: Axial (A) and coronal (B) post-contrast CT lower abdomen and pelvis showing marked irregular circumferential mural thickening of multiple segments of small intestinal loops of soft tissue attenuation (red arrows) with short segments of normal wall thickness in between (skipped segments) (green arrows).Pelvic-free fluid is seen (white arrow)