Positive MITF and NKI/C3 Expression in Cellular Neurothekeoma and Dermatofibroma

Appl Immunohistochem Mol Morphol. 2021 Jul 1;29(6):440-445. doi: 10.1097/PAI.0000000000000889.


Background: Cellular neurothekeoma (CNT) is a benign mesenchymal tumor with uncertain cellular differentiation. Studies have found evidence of myofibroblastic differentiation and possible relation to dermatofibromas (DFs). As microphthalmia transcription factor (MITF) and NKI/C3 stains are routinely positive in CNT, we compared expression patterns of both markers in CNT and DF to assess their relationship.

Materials and methods: We assessed cases of CNT (n=25) and DFs (n=35) for histopathologic characteristics and MITF and NKI/C3 expression. Immunostaining results were classified as negative, focally positive (<50%), and diffusely positive (>50%). At least 1 additional melanocytic marker was assessed in each case of CNT.

Results: Both DFs and CNTs showed a female predilection and a wide age range. Immunostaining in CNTs for MITF was positive in the vast majority (focal 68%, diffuse 24%), as was NKI/C3 (focal 72%, diffuse 24%). All DFs were MITF positive (diffuse 74%, focal 26%), and most DFs were NKI/C3 positive (focal 57%, diffuse 3%).

Conclusion: CNT and DF share demographic, histopathologic, and immunohistochemical features, including shared expression of MITF and NKI/C3, especially cellular DF.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / metabolism*
  • Carcinogenesis
  • Cell Differentiation
  • Child
  • Female
  • Histiocytoma, Benign Fibrous / diagnosis*
  • Histiocytoma, Benign Fibrous / pathology
  • Humans
  • Immunohistochemistry
  • Male
  • Microphthalmia-Associated Transcription Factor / metabolism*
  • Middle Aged
  • Myofibroblasts / pathology*
  • Neurothekeoma / diagnosis*
  • Neurothekeoma / pathology
  • Skin Neoplasms / diagnosis*
  • Skin Neoplasms / pathology
  • Tetraspanin 30 / metabolism*
  • Young Adult


  • Biomarkers, Tumor
  • Microphthalmia-Associated Transcription Factor
  • Tetraspanin 30