Are Stromal Tumor - Reactive Plasma Cells in Mesopharyngeal Squamous Cell Carcinoma a Prognostic Positive Biomarker with Immunomodulatory Potential - A Clinical Case from our Practice

Abstract

Tumour-reactive plasma cells (TRPCs) are part of the tertiary lymphoid structures (TLSs) and have been reported to be positively associated with the longterm survival of patients with various cancers.

We present an inoperable mesopharyngeal squamous cell carcinoma with pronounced stromal tumor-reactive plasma cells infiltration or tumour- infiltrating plasma cells (TIP), which made the pathohistological diagnosis difficult in a 50-year-old patient. Due to the extreme hardness of the tumor, the three biopsies were insufficient material, necessitating the performance of immunohistochemical (IHC) analysis, making the final diagnosis - Undifferentiated squamous cell carcinoma /G3, without keratinization with an abundant plasma cell stromal reaction. A complex treatment was carried out, including preoperative intensity modulated radiotherapy (IMRT) up to total dose 45 Gy, followed by radical tumor resection with clear of tumor cells resection lines and bilateral selective dissection of the suspected metastatic cervical lymph nodes.

Against the background of this clinical case, we present the rarely observed peritumoral tertiary lymphoid structures in mesopharyngeal squamous cell carcinoma, characterized by single tumor cells surrounded by fibrous tissue and an inflammatory infiltrate rich in plasmacytic cells. Our observations regarding the presence of TLSs in an inoperable locally advanced mesopharyngeal tumor confirm increased antitumor immunity that improves treatment outcomes, namely that we were able to achieve local tumor control after preoperative radiotherapy up to TD 45 Gy and salvage surgery.