ABSTRACT
Context: Acute myeloid leukemia (AML) is rarely presented with thrombocytosis and marked thrombocytosis with a platelet count over 1.0×1012/L is an extremely rare phenomenon. Objective: A case of de novo AML with unusual presentation by extreme thrombocytosis. Design: A case report. Setting: Hematology Unit at the Oncology Center Mansoura University, Egypt. Patient: A 37-year-old male patient with a history of sleeve gastrectomy in 2020, presented with oral mucositis, recurrent abscess, fever, and bilateral axillary lymphadenopathy. Initial complete blood count (CBC) showed a Hb level of 6 g/dL, a platelet count of 1.685×109/L, and a white blood cell (WBC) count of 19×109/L. Diagnosis of de novo AML (FAB-M2 AML) was confirmed by bone marrow aspiration, biopsy, and immunophenotyping. Cytogenetic study showed negative t(8;21)/inv 16/ t(9;22). A molecular study showed positive FLT-3 mutation and negative BCP/ABL1, JAK2, V617F, and CALR exon 9 mutations excluding blast transformation on top of myeloproliferative neoplasm (MPN) and myelodysplastic syndrome (MDS). Interventions: The patient received induction chemotherapy including a course of 7-day-cytarabine along with 3-day-anthracycline on September 20th, 2021 but the patient was refractory as BMA showed blast cells 75%. The patient started salvage HAM (high-dose cytosine arabinoside and mitoxantrone) + Sorafenib on November 6th, 2021. Again, he could not achieve a response and received FLAG (high-dose cytosine arabinoside, fludarabine, and granulocyte colony-stimulating factors) + Sorafenib on December 18th, 2021, after recovery from COVID-19 infection. Main Outcome Measures: To shed light on fact that myeloid neoplasms as MPN, MDS, and de novo AML can share overlapping features. Results: On January 25th, 2022, the last CBC showed a Hb level of 8.4 g/dL, a platelet Count of 395×109/L, and a WBC Count of 2.41×109/L with a differential Neutrophil count of 0.24×109/L. The patient lost follow-up since then. Conclusions: Only a few AML cases have been reported with thrombocytosis. Detailed molecular studies are mandatory to confirm the diagnosis of de novo AML patients with unusual presentation. Careful follow-up of those cases could help in establishing management guidelines for better outcomes as those patients usually have a poor prognosis.