Discussion
TAM is a rare hematologic disorder that affects approximately 10-30% of
newborns with Trisomy 21 [8,9]. TAM is characterized by a transient
proliferation of abnormal megakaryoblasts and myeloblasts in the bone
marrow, leading to an excess of immature cells circulating in the
peripheral blood. The underlying molecular mechanism of TAM involves
mutations in the GATA1 gene, which encodes a transcription factor
crucial for normal hematopoiesis. GATA1 mutations are detected in
most patients with TAM and are considered a hallmark of the disease
[10,11]. Notably, the neonate in this case was GATA1 mutation
negative. Despite the absence of a GATA1 mutation, the patient’s
clinical course and laboratory findings strongly supported the diagnosis
of TAM. The extreme thrombocytosis with a platelet count that reached
2,764,000/mL of blood is the highest platelet count ever reported in TAM
upon our review of the literature. Low-dose Cytarabine resulted in a
significant reduction in platelet count after a single cycle. This case
presents extreme thrombocytosis in the setting of TAM in a patient
without a GATA1 mutation, suggesting an alternate molecular
pathway contributing to TAM.