Immunohistochemical analysis of tumors of the salivary glands

Introduction Pleomorphic adenomas (PA) should be surgically resected because of their potential for malignity, but this is not mandatory for other benign tumors. In the case of intraoperative pseudocapsule opening, there is a lifelong risk of recurrence. A reliable diagnosis is currently not possible using CT, MRI or sonography. A preliminary study showed that PA express SSTR21. The aim of this study is the immunohistochemical (ICH) analysis of surface receptors of salivary gland tumors for the expression of SSTR2.

Methods In this unicentric retrospective study, all salivary gland tumors that were surgically resected in our clinic between 03/2016 and 12/2019 were examined using IHC for the SSTR2. IHC evaluation was performed using the HER2-Mama scale.

Results 354 patients were included (99 PA (27.9%), 255 other tumors). Samples were not available for 30 tumors. Another 18 samples were not included because they were cysts. IHC analysis of the remaining 306 tumors (207 non-PA and 99 PA) revealed that the overall percentage of cells staining for SSTR2 was higher in PA. 42.3% of the PA showed >20% of the cells showing the SSTR2 compared to only 1.2% of the other tumors. PA was found to exhibit strong intensity of SSTR2 staining (90.9% ≥ intensity of 2).

Conclusion SSTR2 was strongly expressed in PA. This property may allow radioligated somatostatin analog PET-CT/MR imaging to be used to diagnose PA among other tumors. In addition, SSTR positivity could enable peptide receptor radionuclide or somatostatin analogue therapy in the future.

Publication History

Article published online:
12 May 2023