P166 Histopathological Analysis of Cystic Metastasis in Head and Neck Squamous Cell Carcinoma

Abstract

Objective: Branchiogenic carcinoma is a controversial entity. Some authors believe that the reported cases reflect cystic degeneration of metastatic lymph nodes rather than a primary tumor arising from cyst epithelium. In a previous study, we found evidence of normal epithelium within malignant cysts in 2 cases of possible branchiogenic carcinoma. In contrast, in the setting of a known primary tumor where cystic metastases are present, there is histologically highly dysplastic epithelium lining these degenerative cysts. Our goal was to analyze lymph nodes from patients with head and neck squamous cell carcinoma (SCC), with a documented primary focus, for the presence of normal epithelium within lymph nodes taken during neck dissection. Design: Histologic review of neck dissection specimen slides for evidence of normal epithelium. Patients: Thirty-five patients with known upper aerodigestive tract (UADT) SCC. Interventions: Histopathologic slides from neck dissection specimens were reviewed for histologic evidence of normal squamous epithelium– or epithelial-lined cysts. Results: Fifty neck dissection specimens with 902 lymph nodes were evaluated. Ninety-six nodes were positive for metastatic disease; 15% had evidence of cystic degeneration. None of the lymph nodes evaluated had any evidence of normal epithelium. Conclusions: Cystic degeneration is a frequent phenomenon in metastatic lymph nodes in patients with UADT SCC, but in our study we found no evidence of normal epithelium in any of these cysts. Hence when combined with Martin’s other 3 criteria, the presence of SCC in a normal epithelium–lined cyst is suggestive of branchiogenic carcinoma.