Pseudolymphomatous Atypical Fibroxanthoma

Am J Dermatopathol. 2020 Dec;42(12):972-976. doi: 10.1097/DAD.0000000000001761.


Atypical fibroxanthoma is a rare mesenchymal skin tumor of intermediate malignancy that typically occurs on sun-damaged skin of elderly patients. Histologically, it is composed of pleomorphic cells with hyperchromatic nuclei and abundant cytoplasm, commonly arranged in a spindle cell pattern. Different histologic variants have been described during the past years. We present a case of atypical fibroxanthoma containing a dense inflammatory infiltrate, which in conjunction with the existence of immunoblast-like and Reed-Sternberg-like neoplastic cells could be misinterpreted as a lymphoid neoplasm. Immunohistochemical studies revealed strong positivity of tumor cells for CD10 and negativity for cytokeratins, p63, p40, S100, SOX10, ERG, actin, desmin, B and T-cell markers, BCL6, CD15, and CD30. The inflammatory infiltrate contained a mixed reactive T- and B-cell population with negative T-cell receptor and immunoglobulin heavy rearrangements. We discuss the differential diagnosis of this entity in which clinical, immunohistochemical, and molecular features are essential to avoid the diagnosis of a lymphoproliferative disease.

Publication types

  • Case Reports

MeSH terms

  • Aged, 80 and over
  • Biomarkers, Tumor / analysis
  • Biomarkers, Tumor / genetics
  • Biopsy
  • Diagnosis, Differential
  • Gene Rearrangement, T-Lymphocyte
  • Genes, Immunoglobulin Heavy Chain
  • Genes, T-Cell Receptor
  • Humans
  • Immunohistochemistry
  • Male
  • Neoplasms, Fibrous Tissue / genetics
  • Neoplasms, Fibrous Tissue / immunology
  • Neoplasms, Fibrous Tissue / pathology*
  • Polymerase Chain Reaction
  • Predictive Value of Tests
  • Pseudolymphoma / genetics
  • Pseudolymphoma / immunology
  • Pseudolymphoma / pathology*
  • Skin Neoplasms / genetics
  • Skin Neoplasms / immunology
  • Skin Neoplasms / pathology*


  • Biomarkers, Tumor