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Myeloproliferative neoplasms (MPNs) are classified as chronic myeloid leukemia (CML) and Philadelphia chromosome-negative MPN. In MPN cases, the presence of a BCR-ABL1 translocation with a coexisting mutation is exceptionally rare. Herein, we report the first documented patient with CML harboring CALR mutation in Korea. A 33-year-old woman was referred to our hospital in February 2015 with splenomegaly, leukocytosis, and thrombocytosis. She was diagnosed with CML and started receiving nilotinib. In October 2015, a major molecular response was observed, but thrombocytosis persisted. A repeat bone marrow (BM) examination revealed no specific findings. However, as thrombocytosis worsened, we changed nilotinib to dasatinib. In May 2019, owing to persistent thrombocytosis, we repeated the BM examination and found CALR mutation (15.97%) on the MPN-next generation sequencing (NGS) test. We then retrospectively performed repeat MPN-NGS testing using the BM aspirate sample obtained in 2015 and found CALR mutation (10.64%). [ABSTRACT FROM AUTHOR]

Purpose Primary effusion lymphoma (PEL) is a type of body cavity–based lymphoma (BCBL). Most patients with PEL are severely immunocompromised and seropositive for human immunodeficiency virus (HIV). We investigated the distinctive clinicopathologic characteristics of BCBL in a country with low HIV burden. Materials and Methods We retrospectively collected data on the clinicopathologic characteristics, treatments, and outcomes of 17 consecutive patients with BCBL at nine institutions in Korea. Results Latency-associated nuclear antigen 1 (LANA1) immunostaining indicated that six patients had PEL, six patients had human herpesvirus 8 (HHV8)-unrelated BCBL, and five patients had HHV8-unknown BCBL. The patients with PEL exhibited no evidence of immunodeficiency except for one who was HIV positive. One (20%) and four (80%) patients with PEL and six (100%) and zero (0%) patients with HHV8-unrelated BCBL were positive for CD20 and CD30 expression, respectively. The two patients with PEL (one HIV-positive and one HIV-negative patient) with the lowest proliferation activity as assessed by the Ki-67 labeling index survived for > 1 and > 4 years without chemotherapy, respectively, in contrast to the PEL cases in the literature, which mostly showed a high proliferation index and poor survival. Conclusion PEL mostly occurred in ostensibly immunocompetent individuals and had a favorable outcome in Korea. A watchful waiting approach may be applicable for managing HIV-seronegative patients with PEL with a low Ki-67 labeling index. A possible trend was detected among LANA1, CD20, and CD30 expression in BCBL. [ABSTRACT FROM AUTHOR]