Recognition of appendicitis in the child with hematologic malignancymay be difficult particularly in the setting of neutropenia and multiple medications causing an altered inflammatory response. Typhilitis may produce a similar constellation of clinical findings causing further diagnostic confusion. This review compares the relative frequency of these two conditions in children with hematologic malignancy with a focus on the clinical presentation, distinguishing features, surgical management, and outcome for patients with appendicitis. This institutional review board-approved retrospective study evaluated 464 pediatric patients treated for hematologic malignancy at our institution from 1997 to 2003. From this cohort, we identified all children with a diagnosis of appendicitis or typhilitis. Data include demographics, clinical presentation, laboratory studies, and computed tomography (CT) scan findings. Groups were compared using the Fisher exact test. Significance was defined as P <.05. Eight (1.7%) of 464 children were diagnosed with typhilitis and 7 (1.5%) with appendicitis. There were no demographic differences between patients with appendicitis and typhilitis. Distinguishing clinical features in children with typhilitis included presence of fever and diarrhea. Clinical presentation in children with appendicitis was atypical in 5 of 7 cases yielding an incorrect preoperative diagnosis in all 5. Radiographic evaluation by CT scan accurately defined typhilitis, but not appendicitis. An operation was performed on all 7 children with appendicitis with no operative morbidity or mortality. Appendicitis and typhilitis occur with similar frequency in children with leukemia and lymphoma. Typhilitis is accurately diagnosed with clinical findings of fever, diarrhea, abdominal pain, and typical CT scan findings. Appendicitis tends to present with atypical findings, but can be successfully managed with standard surgical care. Recognition of appendicitis in the child with hematologic malignancymay be particularly difficult in the setting of neutropenia and multiple medications causing an altered inflammatory response. Typhilitis may produce a similar constellation of clinical causes causes further diagnostic confusion. This review compares the relative frequency of these two conditions in children with hematologic malignancy with a focus on the clinical presentation, distinguishing features, surgical management, and outcome for patients with appendicitis. This institutional review board-approved retrospective study evaluated 464 pediatric patients treated for hematologic malignancy at our institution from 1997 to 2003. From this cohort, we identified all children with a diagnosis of appendicitis or typhilitis. Data include demographics, clinical presentation, laboratory studies, and computed tomography (CT) scan findings. Groups were compared using the Fisher exact test. Significance was defined as P < .05 There were no demographic differences between patients with appendicitis and typhilitis. Distinguishing clinical features in children with typhilitis included presence of fever and diarrhea. Clinical presentation in children with appendicitis was atypical in 5 of 7 cases yielding an incorrect preoperative diagnosis in all 5. Radiographic evaluation by CT scan exactly defined typhilitis, but not appendicitis. An operation was performed on all 7 children with appendicitis with no operative morbidity or mortality. Appendicitis and typhilitis occur with similar frequency in children with leukemia and lymphoma. Typhilitis is accurately diagnosed with clinical findings of fever, diarrhea, abdominal pain, and typical CT scan findings. Appendicitis tends to present with atypical findings, but can be successfully managed with standard surgical care.