Parvovirus-induced red blood cell aplasia. A patient with hereditary spherocytosis presented with severe anemia and reticulocytopenia. The marrow showed giant pronormoblasts (with size comparable to that of megakaryocytes) and absence of normoblasts. The condition can be mistaken for marrow involvement by large-cell lymphoma. (Courtesy of K.F. Wong and J.K.C. Chan, Department of Pathology, Queen Elizabeth Hospital, Hong Kong.)