Imaging in Oncology

Imaging in Oncology (Answer)

Answer:

4. intussusception with small bowel obstruction secondary to lymphomatous bowel involvement, and mesenteric adenopathy (Figs 2A-B, Fig 3)

Evaluating the patient with abdominal pain is particularly challenging for the physician. The numerous diagnostic possibilities include both life-threatening and trivial etiologies. The cause of abdominal pain can be difficult to diagnose because it is a common and subjective symptom that is associated with a broad group of diseases.

Acute abdominal pain accounts for approximately 5% of all visits to the emergency department. Although nonspecific abdominal pain is the most common diagnosis for these patients, abdominal pain represents one third of all problems classified as surgical. The initial clinical assessment of the patient with acute abdominal pain includes an adequate history and a physical examination. Characterizing the nature and course of the patient's chief symptom — pain — and eliciting contributory symptoms as well as a pertinent recent and past medical history are the objectives in obtaining an adequate history. An appropriate differential diagnosis can be established by combining the physical findings and clinical history with the examiner's knowledge of pathophysiology and anatomy. Extra-abdominal causes of the pain should also be considered.

A carefully recorded history and a thorough physical examination permit a focused laboratory analysis that can provide supportive information for presumptive diagnoses. Numerous laboratory and adjunctive tests can be obtained. Selection of the necessary studies is important to arrive at the correct diagnosis promptly and cost effectively.[1]

If additional information is required, multiple imaging modalities are available for the evaluation of intra-abdominal causes of pain. Available modalities include plain film radiography, which can detect free intraperitoneal air secondary to a perforated viscus, detect and localize the site of bowel obstruction, detect pathologic calcifications, and screen the lungs as clinically warranted. Positive findings are detected on plain film examination in 10% to 38% of studies.[2-5] Additional modalities include the intravenous urogram, which can evaluate expected urinary tract obstruction or ischemia. A barium enema can help to investigate clinically expected intussusception, colonic obstruction, diverticulitis, and colonic volvulus. Inflammatory and infectious diseases of the esophagus, stomach, and small bowel (including peptic ulcer disease) can be evaluated with an upper gastrointestinal series and/or small bowel study. These studies can also identify less common entities associated with abdominal pain (eg, malrotation with midgut volvulus, intussusception, bowel wall ischemia, or intramural hemorrhage). Angiography can be helpful in the diagnosis and possibly the treatment of gastrointestinal bleeding and gastrointestinal ischemia. Radionuclide imaging can be used to evaluate suspected gastrointestinal bleeding, suspected cholecystitis, other causes of biliary tract obstruction, and infectious or inflammatory bowel disease. Sonography is particularly helpful in the evaluation of cholecystitis, obstructive uropathy, appendicitis, tubo-ovarian abscess, and ectopic pregnancy.

CT scans can support the clinical diagnoses of urinary tract obstruction and bowel obstruction, as well as identify the underlying causes of these abnormalities. Free intraperitoneal air secondary to a ruptured viscus and bowel wall abnormalities, including pneumatosis, can be visualized. Underlying abdominal mass or collection (eg, abscess) contributing to the patient's pain is also easily assessed with CT scans. Additional retro-peritoneal structures, including the pancreas (in the patient with pancreatitis) or vascular structures (eg, a leaking abdominal aortic aneurysm), are also easily evaluated radiographically with CT. CT scans should be used to support clinical diagnoses.[6-8]

Endoscopy — including endoscopic retrograde cholangiopancreatography, esophagogastroduodenoscopy, and colonoscopy — is also an integral adjunctive diagnostic and a therapeutic procedure in the evaluation and treatment of patients with abdominal pain. In the appropriate clinical setting, entities such as gastritis, esophagitis, peptic ulcer disease, colitis, inflammatory bowel disease, and diverticulitis are evaluated with endoscopy.

The present study demonstrated bulky, mesenteric adenopathy, small bowel obstruction, and a heterogeneous posterior right lower quadrant mass. Further evaluation of the right lower quadrant mass revealed concentric rings including a central cylinder (comprised of the lumen and wall of the intussusceptum), a middle cylinder (representing the crescent of mesenteric fat), and an outer cylinder (consisting of the intussuscipiens). These findings represent the classic radiographic appearance of an intussusception. The submucosal lymphomatous nodules, the most prominent of which are seen in the region of the ileocecal valve, represented the lead point in this case. The gross pathologic specimen demonstrated excellent radiologic pathologic correlation of these findings. Microscopic description further demonstrated diffuse lymphomatous mucosal infiltration.

Six percent of intussusception occurs in adults, with a specific etiology identified in 80% of these cases. A benign neoplasm is identified in approximately one third of cases, while a malignant neoplasm is found approximately 20% of the time. Additional causative entities include lipoma, Meckel diverticulum, prolapsed gastric mucosa, aberrant pancreas, adhesions, foreign bodies, feeding tubes, chronic ulcers (tuberculosis/typhoid), prior gastroenteritis, gastroenterostomy, trauma, celiac disease, scleroderma, Whipple's disease, fasting, anxiety, and agonal state. Ileo-ileal intussusception and ileocolic intussusception are most common, representing 40% and 13% of these cases, respectively. No abnormality is identified on plain film radiography in approximately 25% of cases, although a soft tissue mass or small bowel obstruction with nipple-like termination of gas shadow may be identified. An antegrade barium study (ie, upper gastrointestinal series) may demonstrate a "coiled spring" appearance with a beak-like abrupt narrowing of the barium column and a central channel. A retrograde barium study (ie, barium enema) may demonstrate a convex intracolic mass and a "coiled spring" pattern. Ultrasound can also be used in this evaluation to demonstrate concentric rings of alternating hypoechoic and hyperechoic layers, which are referred to as the "donut/target/bull's-eye sign" on transverse sections and the "pseudokidney sign" on longitudinal sections. A complication of intussusception includes perforation (0.4%); this is imminent in this case study since pathologic evaluation demonstrated transmural necrosis with hemorrhage.[6,7]

Non-Hodgkin's lymphoma represents 3% of newly diagnosed cancers. Patients who are predisposed to this disease are those with congenital immunodeficiency syndromes, collagen vascular diseases, or organ transplants, those undergoing immunosuppression, and those infected with the human immunodeficiency virus. Extra-nodal sites of involvement are presented in the Table. Colonic lymphoma has been described as either diffuse submucosal nodularity (as in this case) or large ulcerated lesions.[7,9]

The remaining choices (answers 1, 2, 3, and 5) do not explain the appearance of multiple concentric rings in the right lower quadrant. A cecal volvulus is classically associated with a "kidney-shaped" distended cecum and is usually positioned in the left upper quadrant. Ischemic colitis representing diminished blood flow within the bowel wall presents as a symmetrical lobular segmental thickening of the colonic wall on CT scans with an irregularly narrowed atonic lumen (thumbprinting). Intramural gas and/or portal or mesenteric venous air, as well as thrombus within a superior mesenteric vessel, occasionally can be seen. Bowel obstruction is present in this case; however, it is not secondary to extrinsic compression as suggested in answer 3. Answer 5 (typhlitis with small bowel obstruction) represents a transmural necrotizing inflammatory process of the cecum in neutropenic patients. On CT scan, this may manifest as circumferential cecal wall thickening (greater than 1 to 3 mm) and may also demonstrate intramural pneumatosis as well as pericolonic inflammation.[6,7]

This patient underwent exploratory laparotomy and right hemicolectomy. She tolerated the procedure well with no major postoperative complications.

References

1. Rosen P, Barkin RM, Braen CR, et al, eds. Emergency Medicine: Concepts and Clinical Practice. 3rd ed. St. Louis, Mo: Mosby Year-Book Inc; 1992.
2. Eisenberg RL, Heineken P, Hedgcock MW, et al. Evaluation of plain abdominal radiographs in the diagnosis of abdominal pain. Ann Surg. 1983;197:464-469.
3. McCook TA, Ravin CE, Rice RP. Abdominal radiography in the emergency department: a prospective analysis. Ann Emerg Med. 1982;11:7-8.
4. Lee PW. The plain x-ray in the acute abdomen: a surgeon's evaluation. Br J Surg. 1976;63:763-766.
5. Campbell JP, Gunn AA. Plain abdominal radiographs and acute abdominal pain. Br J Surg. 1988;75:554-556.
6. Putnam CE, Raven CE, eds. Textbook of Diagnostic Imaging. Philadelphia, Pa: WB Saunders Co; 1988.
7. Dahnert W. Radiology Review Manual. 2nd ed. Baltimore, Md: Williams and Wilkins; 1993.
8. Kapoor W, Hemmer K, Herbert D, et al. Abdominal computed tomography: comparison of the usefulness of goal-directed vs non-goal-directed studies. Arch Intern Med. 1983;143:249-251.
9. Williams SM, Berk RN, Harned RK. Radiologic features of multinodular lymphoma of the colon. AJR Am J Roentgenol. 1984;143:87-91.

Back to Cancer Control Journal Volume 4 Number 1