Diagnostic utility of SOX10 immunostaining in benign lichenoid keratosis: A study of 21 cases

J Cutan Pathol. 2023 Jan;50(1):51-55. doi: 10.1111/cup.14318. Epub 2022 Sep 12.


Background: Benign lichenoid keratosis (BLK) is a cutaneous lesion that can clinically mimic malignancy and may represent regression of a pre-existing lesion. BLK may show epidermal pseudo-nests prompting evaluation for a melanocytic lesion. False positivity of MART-1/Melan-A immunostaining in pseudonests has been showed; however, the value of SRY-related HMG-box 10 (SOX10) staining in BLK with features suspicious for a melanocytic proliferation has not been previously reported.

Methods: Twenty-one cases of BLK from 2015 to 2020 were identified. Slides were reviewed and SOX10 immunohistochemistry was performed on each case. Subsequently, Melan-A immunohistochemical staining was performed on all cases.

Results: In 10 cases (47.6%), unexpected SOX10 staining was seen in rare to numerous small, single cells in the epidermis above the basal cell layer. No malignancy was identified. Of the 10 cases, 8 (80%) showed suprabasal SOX10 staining did not show similar suprabasal Melan-A staining; 2 (20%) cases showed scattered suprabasal cells positive for Melan-A.

Conclusion: SOX10 immunostaining in BLK can highlight scattered cells in the epidermis (not easily noticeable on routine stain). Performing SOX10 immunostain alone on BLK can prompt a misdiagnosis of a melanocytic lesion and should be done with caution.

Keywords: Melan-A; SOX-10; benign lichenoid keratosis; passenger melanocytes.

MeSH terms

  • Acanthoma* / pathology
  • Biomarkers, Tumor
  • Humans
  • Keratosis, Actinic* / diagnosis
  • MART-1 Antigen
  • Melanocytes / pathology
  • SOXE Transcription Factors
  • Skin Diseases* / pathology
  • Skin Neoplasms* / diagnosis
  • Skin Neoplasms* / pathology


  • MART-1 Antigen
  • Biomarkers, Tumor
  • SOX10 protein, human
  • SOXE Transcription Factors