Extramedullary myeloid cell tumors. An immunohistochemical and morphologic study of 28 cases

Am J Surg Pathol. 1993 Oct;17(10):1011-9. doi: 10.1097/00000478-199310000-00006.


In an attempt to correlate the morphologic and immunophenotypic findings in extramedullary myeloid cell tumors (EMT), we studied 28 cases with a large panel of antibodies using paraffin section immunohistochemistry. A previous or concurrent diagnosis of acute myelogenous leukemia or chronic myelogenous leukemia was made in 25 cases. Six EMT were morphologically classified as well differentiated (WD-EMT), 17 as poorly differentiated (PD-EMT), and five as blastic EMT. The WD-EMT were easily recognized morphologically and displayed a relatively mature myeloid phenotype, with elastase, CD15, and CD68 positivity in all cases. On the other hand, the five blastic-EMT displayed no morphologic evidence of myeloid derivation, were completely negative for CD15, and were weakly positive for elastase in only one case. The PD-EMT, with a morphologic appearance that resembles large cell non-Hodgkin's lymphoma, variably expressed CD15 and elastase. CD68 and lysozyme were present in the majority of PD-EMT, with some variability, but were negative in most blastic-EMT. CD45 (LCA) was detected in 75% of all EMT and CD34 was positive in 36%; neither antigen was significantly associated with a specific morphology. CD30 reactivity was not evident in any case, but slight positive staining was seen with CD20 (L26) in one WD-EMT. CD43 (Leu 22) was the only antibody that was positive in 100% of cases; staining was always intense and widespread. Antimyeloperoxidase (MPO) was positive in all cases but two, both with a blastic morphology. We conclude that (a) an immunohistochemical panel including CD20, CD43, CD68, and MPO can successfully identify the vast majority (96%) of EMT in paraffin sections, and (b) there is an association between morphology and phenotype in these lesions.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, Differentiation / analysis
  • Antigens, Neoplasm / analysis
  • Flow Cytometry
  • Humans
  • Immunophenotyping
  • Leukemia, Myeloid / classification
  • Leukemia, Myeloid / immunology*
  • Leukemia, Myeloid / pathology*
  • Sarcoma / classification
  • Sarcoma / immunology*
  • Sarcoma / pathology*


  • Antigens, Differentiation
  • Antigens, Neoplasm