104 A rare case of oropharynx primary combined squamous cell carcinoma and small cell carcinoma diagnosed in a biopsy of right piriform sinus mass

Introduction/Objective This case presents a rare, combined tumor in the larynx and oropharynx, consisting of small cell carcinoma (SCC) and squamous cell carcinoma (SqCC), known as a composite neoplasm. Such cases are extremely rare and behave very aggressively. Methods/Case Report A 77-year-old male presented with a large exophytic laryngeal mass involving the right piriform sinus and aryepiglottic fold, along with right cervical lymphadenopathy. A biopsy of the mass was obtained, followed by immunohistochemical stains to identify the tumor’s components. The squamous cell component was tested for CK5/6, p40, and Keratin cocktail, while the neuroendocrine component was tested for Synaptophysin. Histology revealed two distinct populations of tumor cells: one with squamous features and the other with neuroendocrine features. The squamous cells were positive for CK5/6 and p40, while the neuroendocrine cells were positive for Synaptophysin. The lymph node aspiration showed only small cell carcinoma. Results NA Conclusion This rare case highlights the aggressive nature of combined small cell and squamous cell carcinoma of the larynx. The tumor’s complexity stresses the need for better-defined therapeutic strategies.