CT is a highly accurate, noninvasive test for appendicitis, but the optimal CT technique is controversial. Major complications of appendicitis (perforation, abscess formation, peritonitis, bowel obstruction, septic seeding of mesenteric vessels, gangrenous appendicitis) and their management are discussed. Abdominal CT is a well-established technique in the study of acute abdominal pain and has shown high sensitivity and specificity for diagnosing and differentiating appendicitis, providing an accurate diagnosis in the early stages of disease.

Extranodal lymphoproliferative diseases are common, and their prevalence is increasing. Non-Hodgkin lymphomas and Hodgkin disease, in particular, frequently involve extranodal structures in the abdomen and pelvis, including both the solid organs (liver, spleen, kidneys, and pancreas) and the hollow organs of the gastrointestinal tract. Because virtually any abdominopelvic tissue may be involved, many different imaging manifestations are possible, and lymphoproliferative diseases may mimic other disorders. Familiarity with the imaging manifestations that are diagnostically specific for extranodal lymphoproliferative diseases is important because imaging plays an important role in the noninvasive management of disease. However, a definitive diagnosis requires a biopsy (of bone marrow, a lymph node, or a mass), a peripheral blood analysis, and other laboratory tests. In patients with known disease, the goals of imaging are staging, evaluation of response to therapy, and identification of new or recurrent disease or of complications of therapy. In patients without known disease, imaging permits a provisional diagnosis.