F-18 FDG PET/CT Findings of Aggressive NK-Cell Leukemia

Flow Cytometric Immunophenotyping Is Sensitive for the Early Diagnosis of De Novo Aggressive Natural Killer Cell Leukemia (ANKL): A Multicenter Retrospective Analysis

Aggressive natural killer cell leukemia (ANKL) is a fatal hematological neoplasm characterized by a fulminating clinical course and extremely high mortality. Current diagnosis of this disease is not effective during the early stages and it is easily misdiagnosed as other NK cell disorders. We retrospectively analyzed the clinical characteristics and flow cytometric immunophenotype of 47 patients with ANKL. Patients with extranodal NK/T cell lymphoma, nasal type (ENKTL) and chronic lymphoproliferative disorder of NK cell (CLPD-NK), who were diagnosed during the same time period were used for comparisons. Abnormal NK cells in ANKL were found to have a distinctiveCD56bright/CD16dim immunophenotype and markedly increased Ki-67 expression, whereas CD57 negativity and reduced expression of killer immunoglobulin-like receptor (KIR), CD161, CD7, CD8 and perforin were exhibited compared with other NK cell proliferative disorders (p<0.05). The positive rates of flow cytometry detection (97.4%) was higher than those of cytomorphological (89.5%), immunohistochemical (90%), cytogenetic (56.5%) and F-18 fluorodeoxyglucose positron emission tomography/computer tomography (18-FDG-PET/CT) examinations (50%) (p<0.05). ANKL is a highly aggressive leukemia with high mortality. Flow cytometry detection is sensitive for the early and differential diagnosis of ANKL with high specificity.

Increased bone marrow uptake of 18F-FDG in leukemia patients: preliminary findings

The aim of this retrospective study was to evaluate the characteristics of increased bone marrow uptake of 18F-FDG in patients with leukemia who underwent whole-body 18F-FDG PET/CT. The 18F-FDG PET/CT images of 9 patients with histologically proven leukemia were reviewed. The accumulation of 18F-FDG in the bone marrow was evaluated, and was compared with histological subtype, clinical course, and hematological findings. Nine patients (4 males, 5 females; age range, 5-58 years) had increased bone marrow uptake of 18F-FDG, including 6 patients with acute lymphoblastic leukemia, 1 with acute myeloid leukemia, 1 with chronic myeloid leukemia, and 1 with mature B cell neoplasm. Bone marrow uptake was generally diffuse but focal or inhomogeneous uptake was common, especially in the upper and lower extremities. Patients with increased bone marrow uptake of 18F-FDG commonly complained of fever and bone pain. No correlations between 18F-FDG uptake and peripheral blood findings were observed. Patients with leukemia may have increased bone marrow uptake of 18F-FDG on PET/CT, possibly reflecting leukemic cell activity. Leukemia can be included in the differential diagnosis when increased bone marrow uptake of 18F-FDG is observed.

Abnormal immunophenotype provides a key diagnostic marker: a report of 29 cases of de novo aggressive natural killer cell leukemia

Aggressive natural killer (NK) cell leukemia (ANKL) is a systemic neoplastic proliferation of NK cells with an aggressive clinical course. Currently, the diagnosis of ANKL remains challenging. In the current study, we report the clinical, laboratory, immunophenotypic, and genetic findings from 29 cases of de novo ANKL in a single center and evaluate the relative contribution of these features to the diagnosis of ANKL. Clinical features, laboratory findings, morphologic, cytogenetic features, and Epstein-Barr virus status were important factors for diagnosing aggressive NK cell leukemia. On the other hand, ANKL displays a strikingly abnormal immunophenotype in contrast to nonneoplastic NK cells. The immunophenotype of ANKL cells may differ from reactive NK cells in 4 respects. First, the CD45/linear side scatter gating of flow cytometry allows the initial identification of neoplastic subpopulations for additional immunophenotypic analysis in half of ANKL cases. Second, unusual expression of surface antigens in ANKL cells was a prominent feature. Third, the clonality of ANKL cells could be identified using antibodies against CD158a/h, CD158b, or CD158e. Last, the positive rate of Ki-67 expression in ANKL cells was generally high. Based on these findings, we provide an objective marker based on clinical data for the definite diagnosis of ANKL.

Significant contribution of Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in a case of acute lymphoblastic leukemia presenting with fever of unknown origin

The diagnostic value of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) has not been thoroughly evaluated in patients with leukemia. We herein report the case of a patient with B cell acute lymphoblastic leukemia (ALL) presenting with fever of unknown origin (FUO) who was diagnosed after FDG PET/CT indicated diffuse bone marrow involvement.

18F-FDG PET for diagnosis and response assessment for aggressive NK cell leukemia

Aggressive natural killer cell leukemia (ANKL) is a rare malignant disorder of mature NK cells characterized by aggressive clinical course and poor outcome. The commonly involved sites are peripheral blood, bone marrow, liver, and spleen, but any organ can show involvement. We report a case of ANKL diagnosed and assessed the clinical response with 18F-FDG PET. Pretreatment and posttreatment FDG PET/CT showed a high correlation with pathologic diagnosis and staging as well as in the follow-up assessment of the clinical response. FDG PET could be a valuable tool enabling comprehensive staging and follow-up of ANKL.