Yusei Aoki

Clinical and biological significance of CD56 antigen expression in acute promyelocytic leukemia.

The biological significance of CD56 antigen expression in patients with acute promyelocytic leukemia (APL) has been under investigation. We investigated the clinical and biologic features of CD56+APL. In our series, CD56 antigen was positive in 4 of 28 (14%) APL patients. No differences were found regarding age, gender, performance status (PS), initial leukocyte and platelet counts, lactate dehydrogenase (LDH) and fibrinogen (Fbg) levels according to CD56 expression. CD34 antigen was co-expressed in 3 of the 4 patients with CD56+ APL, in contrast to 2 of the 24 patients with CD56- APL (P = .01). Extramedullary relapse occurred in 3 of the 4 patients with CD56+ APL, in contrast to none of the 24 patients with CD56- APL (P = .001). Median remission duration was 4 months in CD56+ APL and was not reached in CD56- APL. The CD56+ population had a shorter remission duration (P < .0001) and disease-free survival (P < .0001). In contrast, no difference was found in overall survival. These results suggested that CD56 expression was associated with the leukemogenetic mutation at the primitive hematopoietic progenitor cell level and extramedullary relapse in APL patients treated with ATRA and chemotherapy.

Distinguishing between proliferating nodal lymphoid blasts in chronic myelogenous leukemia and non-Hodgkin lymphoma : Report of three cases and detection of a bcr/abl fusion signal by single-cell analysis

Lymph node biopsies were analyzed from three patients with chronic myelogenous leukemia (CML) showing nodal blast proliferation. Immunohistochemically, the blasts from all three patients had an immature marker profile with a T‐blast population (cCD3+, CD4–, CD7+, CD8–, CD99+, terminal deoxynucleotidyl transferase +) and a hematopoietic progenitor cell marker (CD34). In two patients, the blasts also expressed myeloid lineage specificity (naphthol AS‐D chloroacetate esterase activity and myeloperoxidase positivity). However, it was difficult to distinguish between blast  proliferation  in  CML  and  non‐Hodgkin  lymphoma from these immunohistopathological findings alone. Subsequently, bcr gene rearrangement and bcr/abl mRNA expression were detected by Southern blot and reverse transcription‐polymerase chain reaction analysis of the lymph nodes. Fluorescence in situ hybridization (FISH) analysis of lymph node touch smears also disclosed bcr/abl gene fusion signals in the blasts of all patients, confirming that the blasts were derived from Philadelphia chromosome‐positive CML. Accurate discrimination between the proliferating nodal blasts of CML and non‐Hodgkin lymphoma is essential for determining subsequent therapy. FISH analysis of bcr/abl in single‐cell blast preparations is an efficient tool that allows rapid, accurate cytopathological diagnosis of extramedullary blast‐phase CML and its discrimination from non‐Hodgkin lymphoma.