Leukemia Presenting as Solid Tumors: Report of Four Pediatric Cases and Review of the Literature

Leukemias are neoplasms that arise from the hematopoetic cells of bone marrow and usually spread first to peripheral blood. Involvement of extramedullary tissue during the course of a leukemia is common and usually does not represent a major diagnostic challenge when the history is available and specimen triage is optimal. In the context of a myeloid origin, extramedullary leukemias are referred to as granulocytic sarcomas, extramedullary myeloid tumors, extramedullary leukemias, or myeloid sarcomas. In the lymphoid category, leukemia involvement of tissue is conventionally distinguished from lymphoma by establishing the presence of 20% or more blasts in the bone marrow. A leukemia with ail initial presentation outside the bone marrow mimicking a solid tumor is a rare but well-documented clinical encounter. Diagnostic difficulties may arise, especially when a specimen is not triaged properly due to the clinical presumption of a nonhematopoietic tumor. Systematic handling and proper triaging of biopsies are the keys to reducing diagnostic error and facilitating a timely diagnosis in this category. We report 4 case examples in the pediatric Population, presenting in different anatomic sites. The value of fresh specimens and performing touch imprints is discussed and emphasized.