Are micromegakaryocytes specific for refractory cytopenia of childhood (RCC)? A study of 38 pediatric patients with thrombocytopenia unrelated to RCC

Leuk Res. 2016 Aug:47:84-7. doi: 10.1016/j.leukres.2016.05.015. Epub 2016 May 24.


Background: 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.

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

Result: 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).

Conclusion: 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.

Keywords: Marrow fibrosis; Micromegakaryocytes; Myelodysplastic syndrome; Refractory cytopenia of childhood; Thrombocytopenia.

MeSH terms

  • Adolescent
  • Bone Marrow Examination
  • Child
  • Child, Preschool
  • Diagnosis, Differential
  • Humans
  • Infant
  • Integrin beta3 / analysis
  • Megakaryocytes / pathology*
  • Myelodysplastic Syndromes / diagnosis*
  • Myelodysplastic Syndromes / pathology
  • Primary Myelofibrosis
  • Reticulin / analysis
  • Thrombocytopenia / complications
  • Thrombocytopenia / pathology*


  • ITGB3 protein, human
  • Integrin beta3
  • Reticulin