A 10-YEAR-OLD boy was seen for a 3-day history of right-sided abdominal pain, widespread cutaneous petechiae, and a 2-day history of fever (temperatures up to 39°C). A pertinent finding from medical history was a diagnosis of lymphoblastic lymphoma 2½ years previously. He had a relapse 1 year previously with acute myeloblastic leukemia and underwent bone marrow transplantation 8 months previously. He had another relapse with acute myeloblastic lymphoma 1 month prior to this admission, and subsequently received chemotherapy 1 week prior to being seen for right-sided abdominal pain. On physical examination, his abdomen was nondistended but diffusely tender, especially on the right. Diffuse petechiae of the lower extremities were also present. Laboratory results showed pancytopenia with neutropenia (hematocrit level, 0.20; white blood cell count, 1.83 × 109/L; and platelet level, 2 × 109/L). After a transfusion of platelets and packed red blood cells, he felt subjectively better. His abdomen remained soft with mild tenderness. Abdominal ultrasonography was performed to rule out cholecystitis or possible appendicitis (Figure 1 and Figure 2). Abdominal and pelvic computed tomography (CT) were also performed (Figure 3 and Figure 4).