Discordant lymphoma consisting of splenic mantle cell lymphoma and marginal zone lymphoma involving the bone marrow and peripheral blood: a case report

Transformation of marginal zone lymphoma (and association with other lymphomas)

Marginal zone lymphomas (MZL) are a diverse group of indolent lymphoproliferative disorders that comprise three subtypes: nodal, splenic and mucosal associated marginal zone lymphomas (MALT). Histologic transformation (HT) to an aggressive lymphoma is a rare event that can occur in any subtype, and at lower frequency compared to other indolent non Hodgkin lymphomas (NHL) like follicular lymphoma. There are few data directly associated with risk and prognosis of transformation in MZL. However, recent advances in the understanding of molecular and genetic features of MALT have contributed to an evolving appreciation of HT in this disease. Optimal treatment of HT of MZL remains unknown. Much of the approach to managing transformed MZL is extrapolated from other indolent NHLs.

Discordant bone marrow involvement in non-Hodgkin lymphoma

A discordant lymphoma occurs where 2 distinct histologic subtypes coexist in at least 2 separate anatomic sites. Histologic discordance is most commonly observed between the bone marrow (BM) and lymph nodes (LNs), where typically aggressive lymphoma is found in a LN biopsy with indolent lymphoma in a BM biopsy. Although the diagnosis of discordance relied heavily on histopathology alone in the past, the availability of flow cytometry and molecular studies have aided the identification of this entity. The true prevalence and clinical ramifications of discordance remain controversial as available data are principally retrospective, and there is therefore little consensus to guide optimal management strategies. In this review, we examine the available literature on discordant lymphoma and its outcome, and discuss current therapeutic approaches. Future studies in discordant lymphoma should ideally focus on a large series of patients with adequate tissue samples and incorporate molecular analyses.

Network properties derived from deep sequencing of human B-cell receptor repertoires delineate B-cell populations

The adaptive immune response selectively expands B- and T-cell clones following antigen recognition by B- and T-cell receptors (BCR and TCR), respectively. Next-generation sequencing is a powerful tool for dissecting the BCR and TCR populations at high resolution, but robust computational analyses are required to interpret such sequencing. Here, we develop a novel computational approach for BCR repertoire analysis using established next-generation sequencing methods coupled with network construction and population analysis. BCR sequences organize into networks based on sequence diversity, with differences in network connectivity clearly distinguishing between diverse repertoires of healthy individuals and clonally expanded repertoires from individuals with chronic lymphocytic leukemia (CLL) and other clonal blood disorders. Network population measures defined by the Gini Index and cluster sizes quantify the BCR clonality status and are robust to sampling and sequencing depths. BCR network analysis therefore allows the direct and quantifiable comparison of BCR repertoires between samples and intra-individual population changes between temporal or spatially separated samples and over the course of therapy.

Acute Myeloid Leukemia Evolving from JAK 2-Positive Primary Myelofibrosis and Concomitant CD5-Negative Mantle Cell Lymphoma: A Case Report and Review of the Literature

Primary myelofibrosis (formerly known as chronic idiopathic myelofibrosis), has the lowest incidence amongst the chronic myeloproliferative neoplasms and is characterized by a rather short median survival and a risk of progression to acute myeloid leukemia (AML) noted in a small subset of the cases, usually as a terminal event. As observed with other chronic myeloproliferative neoplasms, the bone marrow biopsy may harbor small lymphoid aggregates, often assumed reactive in nature. In our paper, we present a 70-year-old Caucasian male who was diagnosed with primary myelofibrosis, and after 8 years of followup and therapy developed an AML. The small lymphoid aggregates noted in his bone marrow were neoplastic in nature and represented bone marrow involvement by a CD5-negative mantle cell lymphoma (MCL) that presented without any associated lymphadenopathy. We reviewed the English medical literature to identify a single case report of simultaneous association of AML and a MCL in the bone marrow. The unusual association presented here suggests an increase in observer awareness to apparently benign lymphoid aggregates in chronic myeloproliferative neoplasms.