Background Daratumumab (DARA) is a human monoclonal antibody for the treatment of multiple myeloma (MM). DARA binds to CD38 on RBCs and interferes with detection of RBC alloantibodies. The objective of this study was to evaluate the risk of RBC alloimmunization in MM patients treated with DARA. Materials and methods A retrospective study of the complete serological profile and transfusion history of 45 MM patients received transfusion and treated with DARA from July 2015 to December 2018 was undertaken. All cases with positive Ab screens were treated with DTT to identify RBC alloantibodies. RBC transfusion history was monitored between the first DARA dose to the last or extending to the first negative Ab screen after the last DARA dose if the Ab screen was ever positive. Forty‐six MM patients received transfusion but not DARA were studied as control group. Results Totally 184 Ab screens were done on 45 patients transfused with ABO‐Rh compatible RBCs, phenotypically matched units or both. None of them showed detectable alloantibodies after DTT treatment. The duration of Ab screening positivity varied markedly, ranging from 25 days to 5 months after the last dose. Two of 46 patients in the control group had preexisting alloantibodies but no new alloantibodies were detected during study period. Conclusions Our results indicate that the risk of forming new RBC alloantibodies after transfusion in MM patients treated with current regimens is very low and no DARA‐associated difference in the alloimmunization risk. No significant difference in alloimmunization is detected between ABO‐Rh compatible and phenotypically matched transfusion.

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Activated PI3K-δ syndrome refers to a recently described primary immunodeficiency syndrome consisting of recurrent sinopulmonary infections, lymphadenopathy, mucosal lymphoid aggregates, increased susceptibility to Epstein–Barr virus and cytomegalovirus, and increased incidence of B-cell lymphomas. Variants in PIK3CD, which encodes the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit delta isoform, enhance membrane association and kinase activity, resulting in increased signal transduction through the PI3K–Akt pathway. Whole-exome sequencing revealed a pathogenic PIK3CD variant in a patient with history of immunologic impairment, recurrent sinopulmonary infections, and lymphoid hyperplasia presenting as intussusception. This case illustrates that while lymphoid hyperplasia secondary to immunodeficiency is most often unsurprising and non-threatening, it can present as an emergency-like intussusception.

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Case: A 64-year-old man diagnosed with prostate cancer was incidentally found to have a lesion in his distal femur. Although initially concerning for metastatic prostate cancer, after biopsy by an orthopaedic oncology specialist, a diagnosis of liposclerosing myxofibrous tumor (LSMFT) was confirmed. The lesion was treated with curettage and demineralized bone matrix grafting with close follow-up. Conclusions: This case report illustrates that LSMFT is not confined to the proximal femur and highlights the differences in radiographic appearance between LSMFT and more common metastatic bone lesions.