Adult-onset severe paroxysmal cold hemoglobinuria after COVID-19 successfully treated with sutimlimab.

Paroxysmal cold hemoglobinuria (PCH) is a form of cold autoimmune hemolytic anemia characterized by the presence of the Donath-Landsteiner antibody, which triggers complement-mediated intravascular hemolysis when the body temperature changes from cold to warm. PCH occurs primarily in children as a rare, self-limiting disease following viral infections. In contrast, adult-onset PCH is very rare and associated with a diverse range of underlying conditions, which complicates its management and treatment. We describe a case of adult-onset PCH following COVID-19, effectively managed with a single dose of sutimlimab, a selective classical complement pathway inhibitor. This intervention was performed during a life-threatening hemolytic crisis, at a time requiring swift decision-making when specific tests to differentiate from other hemolytic anemias were not readily available. This case illustrates the potential of using a single dose of sutimlimab to manage life-threatening hemolytic crises in PCH, highlighting the significance of inhibiting the classical complement pathway.

Case report: Common clonal origin of concurrent langerhans cell histiocytosis and acute myeloid leukemia.

Langerhans cell histiocytosis (LCH) and acute myeloid leukemia (AML) are distinct entities of blood neoplasms, and the exact developmental origin of both neoplasms are considered be heterogenous among patients. However, reports of concurrent LCH and AML are rare. Herein we report a novel case of concurrent LCH and AML which shared same the driver mutations, strongly suggesting a common clonal origin.An 84-year-old female presented with cervical lymphadenopathy and pruritic skin rash on the face and scalp. Laboratory tests revealed pancytopenia with 13% of blasts, elevated LDH and liver enzymes, in addition to generalised lymphadenopathy and splenomegaly by computed tomography. Bone marrow specimens showed massive infiltration of MPO-positive myeloblasts, whereas S-100 and CD1a positive atypical dendritic cell-like cells accounted for 10% of the atypical cells on bone marrow pathology, suggesting a mixture of LCH and AML. A biopsy specimen from a cervical lymph node and the skin demonstrated the accumulation of atypical cells which were positive for S-100 and CD1a. LCH was found in lymph nodes, skin and bone marrow; AML was found in peripheral blood and bone marrow (AML was predominant compared with LCH in the bone marrow). Next generation sequencing revealed four somatic driver mutations (NRAS-G13D, IDH2-R140Q, and DNMT3A-F640fs/-I715fs), equally shared by both the lymph node and bone marrow, suggesting a common clonal origin for the concurrent LCH and AML. Prednisolone and vinblastine were initially given with partial response in LCH; peripheral blood blasts also disappeared for 3 months. Salvage chemotherapy with low dose cytarabine and aclarubicin were given for relapse, with partial response in both LCH and AML. She died from pneumonia and septicemia on day 384. Our case demonstrates a common cell of origin for LCH and AML with a common genetic mutation, providing evidence to support the proposal to classify histiocytosis, including LCH, as a myeloid/myeloproliferative malignancy.