Aggressive natural killer cell leukemia presenting with hemophagocytic lymphohistiocytosis

Epstein - Barr virus positive T and NK-cell lymphoproliferations: Morphological features and differential diagnosis

The spectrum of Epstein-Barr virus (EBV)-positive T and NK-cell lymphoproliferations is broad and ranges from reactive self-limited disorders to neoplastic processes with a fulminant clinical course. EBV plays an important role promoting lymphomagenesis, although the precise mechanisms remain elusive. EBV-positive lymphoproliferative disorders (LPD) are more common in East Asia (China, Japan, Korea and Taiwan), and Latin America suggesting a strong genetic predisposition. The revised 2016 World Health Organization (WHO) lymphoma classification recognizes the following malignant NK- and T-cell lymphomas; extranodal NK/T-cell lymphoma, nasal type (ENKTCL), aggressive NK-cell leukemia (ANKL), and the provisional entity within the group of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) "primary EBV-positive nodal T or NK cell lymphoma". Disorders presenting mainly in children and young adults include chronic active EBV infection (CAEBV) - systemic and cutaneous forms - which are not considered malignant disorders but were included in the WHO classification for the first time because of the differential diagnosis with other T- or NK-cell lymphomas. CAEBV, cutaneous form, includes hydroa vacciniforme-like LPD (HV-LPD) and severe mosquito bite allergy (SMBA). Finally, systemic EBV-positive T-cell lymphoma of childhood was recognized as lymphoma because of its fulminant clinical course. Given the shared pathogenesis of these disorders, overlapping features are common demanding a close clinical, morphological and molecular correlation for an accurate diagnosis. This review summarizes the clinical, histopathological and molecular features of EBV-associated T and NK-cell LPD, highlighting the main features that might aid in the differential diagnosis.

Successful Treatment of Pediatric Epstein-Barr Virus-positive Aggressive Natural Killer-Cell Leukemia

Epstein-Barr virus (EBV)-positive aggressive natural killer-cell leukemia (ANKL) is a rare malignancy of mature natural killer cells, with a very poor survival rate. Patients have a rapidly declining clinical course and a poor prognosis, with a median survival of only a few months. Herein, we describe a 16-year-old boy who was diagnosed with EBV-positive ANKL and successfully treated using combination chemotherapy and a subsequent allogeneic hematopoietic stem cell transplantation (alloHSCT). The patient is disease free 4 years and 9 months after alloHSCT. Thus, combination chemotherapy followed by alloHSCT seems to be a promising therapeutic option for EBV-positive ANKL.

Non-EBV-Related Aggressive NK-Cell Leukemia: An Oncohematological Great Imitator

Aggressive natural killer (NK)-cell leukemia (ANKL) is a very rare oncohematological disease among youngsters in Latin America. Its clinical picture imitates a variety of syndromes and diseases due to its pathophysiology. Its diagnosis is relatively simple due to the prominence of NK malignant cells in peripheral blood and its clinical aggressiveness. In certain circumstances though, the presence of blast NK cells and the natural course of the disease can be so modified by the treatment of one of the imitated diseases, especially when using steroids, that it becomes very difficult to diagnose early in its course. We present a case of a 16-year-old Mexican male who initiated symptoms imitating dengue to severe dengue for which he received steroids, apparently inducing a partial remission; he was then diagnosed as having community acquired pneumonia, then sepsis, septic shock w/disseminated intravascular coagulation, primary hemophagocytic syndrome, severe hepatitis, lupus and finally hyper IgE. It was not until 1 day before dying of hemorrhagic shock, a month after initiating symptoms, when the (re)emergence of blast NK cells in peripheral blood allowed the correct diagnosis to be made. Knowledge of ANKL pathophysiology may raise awareness of this multifaceted malignancy and may open up possibilities for its therapy. Gained knowledge can also be used for guiding NK cell evident aggressiveness against other malignancies.

Epstein-Barr virus (EBV)-associated lymphoid proliferations, a 2018 update

Epstein-Barr virus (EBV) has been linked to many human neoplasms including hematopoietic, epithelial, and mesenchymal tumors. Since our original review of EBV-associated lymphoproliferative disorders in 2007, many advances and developments have been reported. In this review, we will examine the recent advances in EBV-associated lymphoid/histiocytic proliferations, dividing them into reactive, B cell, T/NK cell, immunodeficiency-related, and histiocytic/dendritic cell proliferations.

Aggressive mature natural killer cell neoplasms: from epidemiology to diagnosis

Mature natural killer (NK) cell neoplasms are classified by the World Health Organization into NK/T cell lymphoma, nasal type (NKTCL), aggressive NK-cell leukemia (ANKCL) and chronic lymphoproliferative disorders of NK-cells, the latter being considered provisionally. NKTCL and ANKCL are rare diseases, with higher prevalence in Asia, Central and South America. Most NKTCL present extranodal, as a destructive tumor affecting the nose and upper aerodigestive tract (nasal NKTCL) or any organ or tissue (extranasal NKTCL) whereas ANKCL manifests as a systemic disease with multiorgan involvement and naturally evolutes to death in a few weeks. The histopathological hallmark of these aggressive NK-cell tumors is a polymorphic neoplastic infiltrate with angiocentricity, angiodestruction and tissue necrosis. The tumor cells have cytoplasmatic azurophilic granules and usually show a CD45(+bright), CD2(+), sCD3(-), cytCD3epsilon(+), CD56(+bright), CD16(−/+), cytotoxic granules molecules(+) phenotype. T-cell receptor genes are in germ-line configuration. Epstein-Barr virus (EBV) -encoded membrane proteins and early region EBV RNA are usually detected on lymphoma cells, with a pattern suggestive of a latent viral infection type II. Complex chromosomal abnormalities are frequent and loss of chromosomes 6q, 11q, 13q, and 17p are recurrent aberrations. The rarity of the NK-cell tumors limits our ability to standardize the procedures for the diagnosis and clinical management and efforts should be made to encourage multi-institutional registries.

How I treat hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of pathologic immune activation, occurring as either a familial disorder or a sporadic condition, in association with a variety of triggers. This immune dysregulatory disorder is prominently associated with cytopenias and a unique combination of clinical signs and symptoms of extreme inflammation. Prompt initiation of immunochemotherapy is essential for survival, but timely diagnosis may be challenging because of the rarity of HLH, its variable presentation, and the time required to perform diagnostic testing. Therapy is complicated by dynamic clinical course, high risk of treatment-related morbidity, and disease recurrence. Here, we review the clinical manifestations and patterns of HLH and describe our approach to the diagnosis and therapy for this elusive and potentially lethal condition.

Hemophagocytic lymphohistiocytosis onset during induction therapy for precursor B-cell acute lymphoblastic leukemia

We report the clinical course of a child with precursor B-cell acute lymphoblastic leukemia who developed fever, hepatosplenomegaly, and refractory thrombocytopenia after initiation of chemotherapy. Bone marrow aspiration on Day 8 of induction showed new onset of hemophagocytosis and he met clinical, laboratory, and histopathologic criteria for hemophagocytic lymphohistiocytosis. His symptoms improved significantly after an increased dosage of steroids.