Somatostatin receptor expression in parathyroid neoplasms

Abstract

Introduction Parathyroid carcinoma represents a rare cause of primary hyperparathyroidism. Distinguishing carcinoma from the benign tumors underlying primary hyperparathyroidism remains challenging. The diagnostic criteria for parathyroid carcinoma are local and/or metastatic spreading. Atypical parathyroid adenomas share other histological features with carcinomas but lack invasive growth. Somatostatin receptors are commonly expressed in different neuroendocrine tumors, but whether this also holds for parathyroid tumors remains unknown. Aim Our aim is to examine the immunohistochemical expression of somatostatin receptor 1–5 in parathyroid typical adenomas, atypical adenomas and carcinomas. Methods We used a tissue microarray construct from a nationwide cohort of parathyroid carcinomas (n = 32), age- and gender-matched typical parathyroid adenomas (n = 72) and atypical parathyroid adenomas (n = 27) for immunohistochemistry of somatostatin receptor subtypes 1–5. We separately assessed cytoplasmic, membrane and nuclear expression and also investigated the associations with histological, biochemical and clinical characteristics. Results All parathyroid tumor subgroups expressed somatostatin receptors, although membrane expression appeared negligible. Except for somatostatin receptor 1, expression patterns differed between the three tumor types. Adenomas exhibited the weakest and carcinomas the strongest expression of somatostatin receptor 2, 3, 4 and 5. We observed the largest difference for cytoplasmic somatostatin receptor 5 expression. Conclusions Parathyroid adenomas, atypical adenomas and carcinomas all express somatostatin receptor subtypes 1–5. Somatostatin receptor 5 may serve as a potential tumor marker for malignancy. Studies exploring the role of somatostatin receptor imaging and receptor-specific therapies in patients with parathyroid carcinomas are needed.

Parathyroid Cancer: A Review

“…Similar to other neuroendocrine tumors, parathyroid cancers have also been found to express somatostatin receptors (SSTs). Immunohistochemical studies have shown a prevalence of SST 1–5 within either the cytoplasm or nucleus of parathyroid tumors [68]. The extent of SST 2–5 profile expression is variable, depending on how benign or malignant the tumor is.…”

“…At this time, SST 5 offers us another potential new marker for parathyroid cancer. Similar to the fact that peptide receptor radiotherapy is being utilized in cases of pancreatic neuroendocrine tumors, there may possibly be a role for its utilization in parathyroid carcinoma, although published studies on the same are pending at this time [68].…”

Debulking surgery for functional pleural dissemination of parathyroid carcinoma-case report

“…MIBI scintigraphy reveals uptake of PHPT, thus is useful for localization of ectopic diseases and distant matastasis [ 1 ]. Also, since a parathyroid carcinoma expresses somatostatin receptors, scintigraphy may be beneficial for showing that expression and distant metastasis related to the tumor [ 6 ].…”

Mediastinal Cystic Parathyroid Adenoma Diagnosed by Somatostatin Receptor Scintigraphy

“…A previous study found that normal parathyroid cells express SSTRs ( 8 ). In a recent study, Storvall et al also reported that parathyroid adenomas, atypical adenomas, and carcinomas all express SSTR subtypes 1-5 and suggested that SSTR5 may serve as a potential biomarker for malignancy ( 9 ). Furthermore, long-acting octreotide has been reported as a possible alternative treatment for PHPT due to adenomas in patients with multiple endocrine neoplasia type 1 (MEN1) ( 5 ).…”