In the latest Case Record of the Massachusetts General Hospital, a 4-year-old boy was admitted to this hospital because of fever and abdominal pain. Imaging revealed a periappendiceal mass; purulent fluid was aspirated, and symptoms resolved with antibiotics. One week later, pain recurred. A diagnostic procedure was performed.
Infection is probably the most common cause of abdominal masses in children. Examples of such masses are acute ileitis from infection or Crohn’s disease, perforation of the bowel or appendix by a foreign body, or inflammation of a Meckel’s diverticulum. Intussusception may present with a palpable mass, but patients usually have crampy abdominal pain. A primary psoas abscess is rare and usually is not associated with a palpable mass. By far the most common cause of a mass in the right lower quadrant in a child is acute appendicitis.
• How does the risk of perforation from acute appendicitis differ depending on duration of untreated symptoms?
The risk of perforation is 2% or less among patients with appendicitis who have had untreated symptoms for less than 36 hours; the rate of perforation rises to approximately 5% if symptoms are left untreated for 36 hours or more.
• What is the differential diagnosis of an intestinal neoplasm in a child?
In children, the most common intestinal neoplasms are lymphomas, principally Burkitt’s lymphoma and diffuse large-B-cell lymphoma. Other primary bowel tumors, such as carcinoid tumors, adenocarcinomas, or sarcomas, are unusual. Tumors of the iliac crest, such as osteosarcoma or Ewing’s sarcoma, can present as an abdominal mass, as can rhabdomyosarcoma of the abdominal wall or retroperitoneal muscles.
Morning Report Questions
Q: What are the characteristics and typical presentation of Burkitt’s lymphoma?
A: Burkitt’s lymphoma is an aggressive mature B-cell lymphoma that occurs in patients of all ages. Nearly all cases of Burkitt’s lymphoma have rearrangement of the MYC oncogene with the immunoglobulin heavy-chain (or, less often, the light-chain) locus, leading to up-regulation of MYC expression by immunoglobulin promoters. In the United States, Burkitt’s lymphoma accounts for 40 to 50% of pediatric non-Hodgkin’s lymphomas. Typically, patients with Burkitt’s lymphoma present with a large abdominal mass and abdominal pain and distention, or with intussusception of the small bowel related to lymphoma involving the terminal ileum. Rapid growth is typical of Burkitt’s lymphoma, which has a tumor doubling time of 12 to 24 hours and thus may constitute a true oncologic emergency. Patients need to be evaluated and treated urgently because of the risk of metabolic derangements, the tumor lysis syndrome, and organ compromise from massive intraabdominal disease.
Q: What are the principles of treatment in Burkitt’s lymphoma and what is the prognosis?
A: Burkitt’s lymphoma is highly curable, and the majority of children with the disease are cured with relatively short courses of systemic multiagent chemotherapy. Therapy directed at the central nervous system (in the form of intrathecal chemotherapy) is an essential component of treatment for all patients. Even when the cerebrospinal fluid is negative for tumor cells, because the central nervous system is a sanctuary for tumor cells as well as the fact that relapses are common there and systemic treatments do not penetrate the central nervous system well, intrathecal therapy is a critical part of treatment. Supportive care is also crucial, because of the risk of the tumor lysis syndrome in patients with a large tumor burden; rasburicase (recombinant urate oxidase) has improved the ability to effectively manage this complication.