Human herpesvirus-8 (HHV8)-positive effusion-based lymphomas have been termed primary effusion lymphoma (PEL) in the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. Kaposi sarcoma herpesvirus (KSHV)/HHV8-negative effusion-based lymphomas (KSHV/HHV8-negative EBLs) resembling PELs have been reported in the literature and in many cases have been (mis)classified as PEL-like lymphomas. Herein, we present a series of cases and a review of KSHV/HHV8-negative EBLs. This lymphoma, although cytomorphologically resembling PEL, is a distinct entity with characteristic clinical and pathologic features. Patients are older, generally human immunodeficiency virus negative and not immunosuppressed, frequently hepatitis C positive compared with the population baseline, and often have an underlying medical condition leading to fluid overload. The lymphoma cells express pan-B-cell antigens in 86.7%, and CD20 is expressed in 71.1% of the cases. The lymphoma is often of germinal center B or mixed germinal center B/activated B-cell signature with the Hans classifier, and Epstein-Barr virus is positive in nearly 30% of cases. Rare T-cell lymphomas were also reported. Clinical outcomes and response to therapy, including isolated aspiration, are relatively favorable compared with cases of PEL. We suggest that HHV8-negative effusion-based lymphoma is a distinct entity associated with fluid overload states.

Although KIT mutations are present in 20–25% of cases of t(8;21)(q22;q22) acute myeloid leukemia (AML), concurrent development of systemic mastocytosis (SM) is exceedingly rare. We examined the clinicopathologic features of SM associated with t(8;21)(q22;q22) AML in ten patients (six from our institutions and four from published literature) with t(8;21) AML and SM. In the majority of these cases, a definitive diagnosis of SM was made after chemotherapy, when the mast cell infiltrates were prominent. Deletion 9q was an additional cytogenetic abnormality in four cases. Four of the ten patients failed to achieve remission after standard chemotherapy and seven of the ten patients have died of AML. In the two patients who achieved durable remission after allogeneic hematopoietic stem cell transplant, recipient-derived neoplastic bone marrow mast cells persisted despite leukemic remission. SM associated with t(8;21) AML carries a dismal prognosis; therefore, detection of concurrent SM at diagnosis of t(8;21) AML has important prognostic implications.

Objective. Mutational analysis by next-generation sequencing (NGS) obtained by peripheral blood NGS has been of clinical interest to use as a minimally invasive screening tool. Our study evaluates the correlation between NGS results on peripheral blood and bone marrow in hematolymphoid disease. Method. We evaluated patients who had NGS for presumed hematologic malignancy performed on peripheral blood and bone marrow within a 1-year interval of each other. We excluded cases in which chemotherapy or bone marrow transplant occurred in the interval between the two tests. The concordance across peripheral blood and bone marrow NGS results was assessed by kappa coefficient analysis. Results. A total of 163 patients were studied. Concordance of peripheral blood and bone marrow NGS found in 150 patients (92.0%) with a kappa coefficient of 0.794 (kappa standard error 0.054) and value for testing kappa <0.0001. Myeloid neoplasms showed concordant results in 77/78 cases (98.7%) with a kappa coefficient of 0.916. Lymphoid neoplasms showed concordant results in 26/31 cases (83.9%) with a kappa coefficient of 0.599. Nonneoplastic cases showed concordant results in 47/54 cases (87.0%) with a kappa coefficient of 0.743. Conclusion. Peripheral blood NGS is a reliable tool for mutational analysis and provides a less invasive method for screening and monitoring of the molecular profile.