Left lower quadrant inflammatory mass: clinico-radiologic-pathologic conference

• Published in: Canadian Association of Radiologists journal Vol. 49; no. 4; pp. 232 - 236
• Main Authors: Bach, D B, Levin, M F, Black, R T, Slinger, R
• Format: Journal Article Conference Proceeding
• Language: English
• Published: United States SAGE PUBLICATIONS, INC 01.08.1998
• Subjects: Abscess - complications; Diagnosis, Differential; Gastrointestinal diseases; Humans; Intestinal Diseases - diagnostic imaging; Intestinal Neoplasms - complications; Intestinal Neoplasms - diagnostic imaging; Intestinal Neoplasms - pathology; Intestinal Perforation - diagnostic imaging; Intestinal Perforation - etiology; Intestine, Small - diagnostic imaging; Intestine, Small - pathology; Leukemia, Lymphocytic, Chronic, B-Cell - complications; Leukemia, Lymphocytic, Chronic, B-Cell - diagnostic imaging; Leukemia, Lymphocytic, Chronic, B-Cell - pathology; Male; Middle Aged; Radiography
• ISSN: 0846-5371; 1488-2361

The most common tumour involving the small bowel is metastatic disease. Although there was no history of a tumour in this case, the possibility of metastasis from an occult form of cancer (such as melanoma) could not be excluded. In terms of a primary tumour, adenocarcinoma is more frequent overall than lymphoma in the small bowel. However, adenocarcinoma occurs more often in the duodenum than in the ileum, whereas lymphoma of the small bowel occurs more frequently in the ileum than in the duodenum. Their incidence in the jejunum is roughly equal.(f.3) Other primary tumours of the small bowel include leiomyosarcoma and carcinoid.(f.4) Three types of tumours have a propensity to develop a cavitary mass continuous with the gut: ulcerating adenocarcinoma, leiomyosarcoma and lymphoma. In this case, correct interpretation of the CT examination hinged on the recognition that this large cavitating mass (or abscess), while clearly continuous with the alimentary tube, originated in the small bowel, not the colon, as confirmed by the small-bowel follow-through. On the CT scan, the descending colon could be easily identified in its normal location, in the anterior pararenal space adjacent to the lateroconal fascia (Figs. 1A, 1B).(f.5) If the mass had originated in the colon, adenocarcinoma would have been the most likely diagnosis. However, origin in the mid-small bowel (jejunum or ileum), as in this case, makes lymphoma as likely as adenocarcinoma. Both are more common than leiomyosarcoma. The descriptor "aneurysmal dilatation" warrants further comment. This term, coined in 1885,(f.10) refers to focal dilatation of a segment of bowel involved by lymphoma. This must be distinguished from an abscess cavity that communicates with the bowel (as in this case), and from bowel dilatation that occurs proximal to an obstruction. The mechanism of aneurysmal dilatation in lymphoma is thought by some to be related to infiltration of the muscularis propria and autonomic plexus in the involved area.(f.8) However, lymphoma of the small bowel typically does not involve the nerve fibres. Since aneurysmal dilatation can also be seen in [Crohn]'s disease, this suggests a mechanism other than tumour infiltration of nerve fibres. Infiltration of the muscle layers in the absence of a demoplastic process is one possibility.(f.10)