thrombosis; hemolysis; This literature marketed report has been received from the authors of a published literature article, titled as stated below. It was reported in a Letter to the Editor referring to a 39-year-old female patient. The patient presented with new onset pancytopenia with white blood cell (WBC) 2.85 k/uL, haemoglobin (Hgb) 8.6 g/dL, hematocrit (Hct) 24.2%, mean corpuscular volume (MCV) 99.6 fL, platelets (Plts) 25 k/uL. A bone marrow biopsy revealed a hypocellular marrow (10-30%) with marked granulocytic hypoplasia. Flow cytometry of the peripheral blood for paroxysmal nocturnal hemoglobinuria (PNH) showed a granulocyte clone of 35.32%, type II erythrocyte clone 4.066%, and type III 0.765%. The karyotype was normal and a diagnosis of aplastic anemia (AA)/PNH was made. Testing for Fanconi's anemia was negative and next generation sequencing (NGS) testing revealed absence of any known myeloid mutations. She was treated with immunosuppressive therapy of horse anti-thymocyte globulin (ATG) and cyclosporine (CsA) with minimal complications. Post treatment, she achieved near complete normalization of blood counts with the exception of mild thrombocytopenia, so CsA was continued. Over the course of 3 years since initial diagnosis, her blood counts averaged WBC 2.84 k/uL, absolute neutrophil count (ANC) 1.5 k/uL, absolute lymphocyte counts (ALC) 1.18 k/uL, Hgb 11.08 g/dL and Plt 51 k/uL while her type II PNH erythrocyte clone continued to gradually expand to 36%, type III erythrocyte clone of 1%, and granulocyte clone of 47%, without evidence of hemolysis. She was found to have an elevated D-Dimer of 1660 ng/mL, lactate dehydrogenase (LDH) 347 U/L, and absolute reticulocyte count of 0.094 M/uL. Infectious work-up, computerized tomography (CT) pulmonary angiogram, and peripheral venous vascular ultrasound were negative for infection or clots. She was started on prophylactic anticoagulation due to increased thrombotic risk from her expanding PNH clone and was found to have a transient phosphatidylinositol glycan anchor biosynthesis class A (PIGA mutation p.V205F, variant allelic frequency (VAF) of 15%.  Over the course of the following year, she developed recurrent upper respiratory infections associated with significant hemolysis requiring multiple courses of antibiotics, corticosteroid therapy and red blood cell transfusions. She experienced recurrent hospitalizations. A repeat bone marrow biopsy did not identify any morphological evidence of disease evolution, however, NGS testing detected new acquisition of somatic mutations in Nucleophosmin 1 (NPM1) (p.Trp288Cysfs, VAF: 38%), B-cell lymphoma 6 corepressor (BCOR) (p.Phe1397Glnfs, 38%) and three clones of Wilms' tumour 1 (WT1) (p.Arg246, 5%; p.Ser169, 6% and p.Leu166Profs, 25%). Notably, there was a shift in her clonal dynamic, with her PNH clone dramatically declining in size (type II erythrocyte of 47% declining to 3.31%, type III erythrocyte of 2% declining to 0.1% and granulocyte clone down to 0.27% from 48%) in the absence of active PNH treatment.  Given the recurrent episodes of hemolysis and infections she was initiated on eculizumab and the appropriate pneumococcal vaccine, polyvalent (23-valent)(manufacturer unknown) and meningococcal vaccine (unspecified) vaccines series (for prophylaxis; dose detail, anatomical location, route of administration, batch/lot # and expiration date were not reported) were administered prior to starting C5 complement inhibitors (CI) therapy. Within two weeks of starting eculizumab and completing the course of immunizations, she was found to have systemic painful (palpable) erythematous nodules on her extremities. Eculizumab therapy was discontinued, infectious workup was unrevealing, and the skin biopsy showed thrombotic vasculopathy in small and medium vessels. She was started on high doses of corticosteroids, resumed therapeutic anticoagulation despite a persistent thrombocytopenia, and subsequently reinitiated eculizumab therapy. She had a relapsing/remitting course with systemic painful nodules and minimal improvements in cytopenias. A repeat bone marrow biopsy one month later demonstrated significant dysmegakaryopoiesis and dyserythropoiesis with increased ring sideroblasts consistent with myelodysplastic syndromes (MDS) accompanied by 4% blasts and a normal karyotype. NGS testing identified mutations in NPM1 (p.Trp288Cysfs, 29%), BCOR (p.Phe1397Glnfs, 35%) and two clones of WT1 (p.Ser169, 11% and p.Leu166Profs, 15%). The PNH clone revealed type II erythrocyte of 4.64%, type III erythrocyte of 0.27% and granulocyte clone of 1.66%.  Due to the atypical molecular lesions found on NGS and the small/medium vessel thrombosis on skin biopsy, we further characterized her cells using flow cytometry to sort into PNH (+) and PNH (-). Sequencing analysis revealed the PNH (-) cells harbored the NPM1, BCOR and WT1 mutations. These findings alone demonstrated clonal outgrowth of the PNH clone by the myeloid lineage harboring the NPM1, BCOR, and WT1 mutations. In addition, this illustrated that the size of the PNH clone did not preclude thrombotic complications or hemolysis. Surprisingly, despite presence of a small PNH clone, she may have had an immunogenic response to the timing of the immunizations that ignited active inflammation resulting in thrombosis/hemolysis. With morphologic evidence of progression to MDS and new high-risk mutations, she was evaluated by the transplant team and underwent a hematopoietic stem cell transplant. The outcome of the events was unknown.  The reporter considered thrombosis and haemolysis to be related to pneumococcal vaccine, polyvalent (23-valent)(manufacturer unknown) and meningococcal vaccine (unspecified) vaccines series (reported as an immunogenic response to the timing of the immunizations that ignited active inflammation resulting in thrombosis/hemolysis).  Upon internal review, thrombosis and haemolysis were considered to be medically significant.  A copy of the published article is attached as further documentation of the patient's experience.  Literature Report:.