Pathologic evaluation of inguinal sentinel lymph nodes in vulvar cancer patients: a comparison of immunohistochemical staining versus ultrastaging with hematoxylin and eosin staining.

Objectives: To evaluate the value of immunohistochemical (IHC) staining of inguinal sentinel lymph nodes (SLN) found to be negative for metastatic disease by ultrastaging with hematoxylin and eosin (H&E) staining.

Methods: An IRB approved study identified 29 patients who had undergone an inguinal sentinel lymph node dissection for squamous cell carcinoma of the vulva. All sentinel lymph nodes found to be negative for metastatic disease based on ultrastaging with H&E staining were reevaluated with pancytokeratin antibody (AE1/AE3) immunohistochemical (IHC) staining to detect micrometastasis.

Results: Twenty-nine patients with squamous cell carcinoma of the vulva underwent an inguinal sentinel node dissection. Nineteen patients had inguinal dissections negative for metastatic disease, 2 patients had bilateral inguinal metastasis, and 8 patients had unilateral inguinal metastasis. A total of 42 groin dissections with SLN biopsies were performed; 12 groins were positive for metastatic disease and 30 were negative based on ultrastaging with eosin and hematoxylin staining. A total of 107 sentinel lymph nodes (2.5 SLN per groin) were obtained, of which 18 SLN contained metastatic disease identified by ultrastaging and staining with H&E. Two SLN contained micrometastasis less than 0.3mm in size and 16 SLN contained metastasis greater than 2mm in size. Eighty-nine SLN found to be negative for metastasis by ultrastaging with H&E staining were also negative for micrometastasis on evaluation with pancytokeratin antibody AE1/AE3 IHC staining.

Conclusions: The addition of immunohistochemical staining to ultrastaging with H&E staining in the pathologic evaluation of inguinal sentinel lymph nodes does not increase the detection of micrometastasis in patients with primary squamous cell carcinoma of the vulva.