Are micromegakaryocytes specific for refractory cytopenia of childhood (RCC)? A study of 38 pediatric patients with thrombocytopenia unrelated to RCC.
Micromegakaryocytes (microMKs) are considered the most reliable dysplastic feature for myelodysplastic syndrome (MDS), particularly refractory cytopenia of childhood (RCC); there is no minimal threshold for the diagnosis of RCC. Since most RCC patients present with thrombocytopenia, the presence of microMKs should raise concern for MDS/RCC. This study attempted to investigate the prevalence of microMKs and associated marrow fibrosis in patients with thrombocytopenia unrelated to MDS/RCC and the need for establishing a threshold for microMKs for the diagnosis of MDS/RCC.



Bone marrow biopsies of pediatric patients with thrombocytopenia unrelated to RCC were examined for microMKs and fibrosis by CD61 immunohistochemical and reticulin stains respectively.



Thirty eight patients (1-18 years old) were included: 33 immune thrombocytopenia (ITP), 3 chronic thrombocytopenia, and 2 inherited macrothrombocytopenia. Fourteen cases (37%) had microMKs; four cases showed increased marrow fibrosis associated with microMKs (two had ITP and two had macrothrombocytopenia). All patients are alive and none developed MDS (follow up: 3months to 4 years).



MicroMKs can be seen in pediatric patients with thrombocytopenia unrelated to RCC. Hence the mere presence of microMKs is insufficient for the diagnosis of RCC in the pediatric population, and a quantitative threshold needs to be established.
Department of Pathology & Immunology, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, USA.
Barina
B
Aqil
Department of Pathology & Immunology, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, USA. Electronic address: punia@bcm.edu.
Jyotinder N
JN
Punia
Department of Pathology & Immunology, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, USA.
Choladda V
CV
Curry
Department of Pathology & Immunology, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, USA.
Andrea N
AN
Marcogliese
Department of Pathology & Immunology, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, USA.
M Tarek
MT
Elghetany
D000293:Adolescent; D001856:Bone Marrow Examination; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D006801:Humans; D007223:Infant; D039661:Integrin beta3 / Q000032:analysis; D008533:Megakaryocytes / Q000473:pathology*; D009190:Myelodysplastic Syndromes / Q000175:diagnosis* / Q000473:pathology; D055728:Primary Myelofibrosis; D012155:Reticulin / Q000032:analysis; D013921:Thrombocytopenia / Q000150:complications / Q000473:pathology*
C061248:ITGB3 protein, human; D039661:Integrin beta3; D012155:Reticulin
Marrow fibrosis; Micromegakaryocytes; Myelodysplastic syndrome; Refractory cytopenia of childhood; Thrombocytopenia