Nonossifying fibroma of long bones: An immunohistochemical study

Pablo A. Bejarano, Michael Kyriakos

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2 Scopus citations


Fourteen cases of nonossifying fibroma (NOF) of bone were studied immunohistochemically to elucidate the character of their constituent stromal cells, multinucleated osteoclastic-type giant cells, and foam cells. The stromal spindle cells, the main cellular component of NOF, stained for KP-1 (CD-68), α-1-antichymotrypsin, and HAM-56 in ail cases and were immunoreactive for α-1-antitrypsin and HLA-DR in 13 (93%) cases and for lysozyme in 8 cases (57%). These results indicate that the cells have a histiocytic immunophenotype. However, they also expressed vimentin and muscle-specific actin (MSA) in 14 (100%) and 13 (93%) cases, respectively, indicating that they might also have fibroblastic or myofibroblastic characteristics. This histiocytic-mesenchymal immunophenotype was present in most of the stromal cells; from 50 to 100% of them coexpressed KP-1, vimentin, and MSA. The stromal cells were essentially the only cells reactive for proliferating cell nuclear antigen (PCNA) and Ki-67 antigen, which were present in the cells of 13 (93%) and 10 (77%) of the cases, respectively. The multinucleated giant cells and foam cells also showed immunohistochemical evidence of histiocytic differentiation. The former were reactive for KP-1 in all 14 cases, for lysozyme in 13 (93%), and for α-1-antichymotrypsin in 8 of 13 cases (62%). Foam cells expressed reactivity for KP-1, lysozyme, HLA-DR, and HAM-56 in all of the cases in which they were present, whereas leukocyte common antigen (LCA) expression was present in 66% of the cases. The findings in our study indicate that the stromal cells in nonossifying fibroma are the proliferative elements and that they possess immunohistochemical feature of both histiocytic and fribroblastic-myofibroblastic differentiation. The foam and multinucleated giant cells appear to represent an end stage of cellular development lacking proliferative properties; their origins appear linked to that of the stromal cells. There was no support for the suggestion that NOF is a lipoblastic lesion, as all cells were nonreactive for S-100 protein.

Original languageEnglish (US)
Pages (from-to)257-264
Number of pages8
JournalApplied Immunohistochemistry
Issue number4
StatePublished - Jan 1 1995


  • Fibroblast
  • Histiocyte
  • Immunohistochemistry
  • Metaphyseal fibrous defect
  • Myofibroblast
  • Nonossifying fibroma

ASJC Scopus subject areas

  • Anatomy
  • Medical Laboratory Technology


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