Introduction/Background After the studies that demonstrate the usefulness and benefit of one-step nucleic acid amplification technique (OSNA) in sentinel lymph node biopsy (SLNB) in endometrial and cervical cancer (1–4), we wanted to evaluate the expression of cytokeratin 19 (CK19) in vulvar carcinomas in order to perform intraoperative SLNB using OSNA.

Methodology The expression of CK19 was studied in 37 paraffin tissues from vulvar biopsies diagnosed with squamous cell carcinoma from Donostia Hospital from January 2021 to December 2023.

Results Of the 37 biopsies of Donostia Hospital, 8 were CK 19 positive (22%). Among positive cases, a different rate of staining was observed ( 7–95%). None of the positive cases was associated with HPV.

A relatively different rate of CK19 expression was observed in the literature (5).

Conclusion Despite showing various positivities and in some cases of low rate, the fact of its existence makes considering the study of CK19 with immunohistochemistry in a protocol manner in biopsies of vulvar squamous cell carcinoma; Although special caution and prudence should be taken in cases with a low percentage of expresión, patients who show diffuse positivity could benefit from the intraoperative SLNB study with OSNA, increasing the detection of micrometastases, and avoiding the complications derived from a second intervention.

Disclosures No.