We report two cases of adult acute lymphoblastic leukemia presenting with preleukemic phase of pancytopenia with a few abnormal lymphoid cells in bone marrow aspirates. The initial diagnosis of each case was suspicious aplastic anemia and hypoplastic anemia. Both cases progressed to overt acute lymphoblastic leukemia within 1 year. We suggest that initial pancytopenic phase (pre-ALL) may precede the diagnosis of acute lymphoblastic leukemia in adults and differential diagnosis from myelodysplastic syndrome and primary aplastic anemia will be needed. We also suggest that primary bone marrow lymphoma and "primary unknown metastatic lymphoma of bone marrow" may be possible as the pathogenesis in a case like ours.
Adult ; Anemia, Aplastic/diagnosis ; Bone Marrow/pathology ; Diagnosis, Differential ; Female ; Human ; Leukemia, Lymphocytic, Acute, L2/etiology* ; Leukemia, Lymphocytic, Acute, L2/diagnosis ; Male ; Myelodysplastic Syndromes/diagnosis ; Pancytopenia/etiology* ; Pancytopenia/diagnosis ; Preleukemia/etiology* ; Preleukemia/diagnosis

OBJECTIVETo explore prospective diagnostic criteria for preleukemia.

METHODSA case control study was done comparing the discrepancies on clinical and laboratory features between patients with preleukemia and those with chronic aplastic anemia (CAA) or atypical paroxysmal nocturnal hemoglubinuria (a-PNH).

RESULTSThere were eight variables of significance: (1) lymphocytoid micromegakaryocytes in the bone marrow; (2) immature granulocytes in the peripheral blood; (3) > or = 2.0% myeloblasts in the bone marrow; (4) positive periodic acid schiff (PAS) stained nucleated erythrocytes; (5) myeloid differentiation index > or = 1.8; (6) typical colonal karyotypic abnormalities; (7) negative sister chromatid differentiation; (8) cluster/colony ratio of granulocyte-macrophage colony-forming units (CFU-GM) > 4.0. The following criteria were assigned: A: to meet variable one and at least two of the other seven variables and B: to meet at least four of the eight variables. All of the patients with preleukemia met either A or B and none of the patients with CAA or a-PNH did.

CONCLUSIONSPreleukemia is different from CAA or a-PNH. It has its own clinical and laboratory features, which may be useful for its prospective diagnosis.

Adolescent ; Adult ; Aged ; Apoptosis ; Case-Control Studies ; Chromosome Aberrations ; Female ; Humans ; Immunophenotyping ; Male ; Middle Aged ; Preleukemia ; diagnosis ; genetics ; pathology ; Survival Rate