Do not use fiasp insulin with Tandem ©Sarah Blain1 MD, FRCPCAffiliations :1Fellow of The Royal College of Physicians of Canada in Pediatric Hematologist/Oncologist and PediatricsShort running title: Fiasp insulin causes micro-occlusions of Tandem © insulin pumpCorresponding author:Dr. Sarah Blainsarah.blain@umontreal.caLetter: 1566 wordsArticle contains no table, no figure

Desmoplastic small round cell tumor (DSRCT) is a rare and aggressive sarcoma that most commonly presents in males with abdominal and peritoneal invasion. There are potential curative therapeutic options, but survival remains poor. To this day, there have only been 19 reported cases of primary renal DSRCT in the literature and thoracic DSRCT has been rarely reported with very little known about effective therapy. We present a patient with a case of thoracic relapse of DSRCT after a primary renal lesion and prior history of nodular lymphocyte predominant Hodgkin Lymphoma.

APS is an autoimmune disease in which patients are at increased risk of thrombosis and/or pregnancy complications. CAPS is a form of severe APS with multisystemic involvement and microvascular thrombi. Both entities are treated with anticoagulation and multimodal immunotherapy regimens. We present two APS cases in which patients did not meet criteria for CAPS, but needed CAPS-like treatment to stop the progression of thromboses. This case series stresses the importance of stringent follow-up in APS to ensure regression of thromboses. They also emphasize the need of aggressive immunotherapy in refractory APS.

Gemtuzumab ozogamicin (GO) is an anti-CD33 antibody that is FDA approved in upfront acute myeloid leukemia (AML) for patients over 1 month-old, and for relapsed or refractory AML in patients over 2 years-old. GO is now integrated in upfront pediatric AML treatment, and often in CD33+ relapse treatment combined with intensive conventional chemotherapy. Although GO was initially tested as a monotherapeutic agent in relapsed or refractory AML ([1](#ref-0001) ,[2](#ref-0002)), there are few data in pediatric patients supporting this indication. In this review, we report 4 cases of multiply relapsed pediatric AML patients that were treated with GO monotherapy with palliative intent. Three out of 4 patients obtained a complete response with GO re-induction, either as monotherapy or paired with conventional chemotherapy. Three patients remained in remission respectively for 5, 17, and 9 months with GO continuation monotherapy. The literature was reviewed regarding the use of GO in pediatric AML relapse settings.

Congenital dyserythropoietic anemia type IV (CDAIV) is a rare inherited hematological disorder presenting severe anemia due to altered erythropoiesis and hemolysis, with variable needs for recurrent transfusions. We present a case of a transfusion-dependant male newborn who required an intrauterine transfusion and presented at birth with severe hemolytic anemia. Genetic testing rapidly identified a KLF1 gene mutation, a CDAIV variant. This case highlights the advantages of next-generation sequencing testing for congenital hemolytic anemia: diagnostic speed, guidance on natural history, and optimized clinical management and anticipatory guidance for parents and clinicians. We reviewed the literature for all CDAIV cases.