Commentary: Case Report: Abdominal Lymph Node Metastases of Parathyroid Carcinoma: Diagnostic Workup, Molecular Diagnosis, and Clinical Management

In the issue of March 2021, Lenschow et al. reported the case of a 46-year-old woman with recurrent, programmed death-ligand-1 (PD-L1) negative, tumor mutational burden (TMB)-high parathyroid carcinoma (PC), who showed stable disease as her best response on imaging, and a three-fold drop in PTH after treatment with intravenous pembrolizumab. Parathyroid carcinoma is a rare neuroendocrine tumour, accounting for <1% of all cases of primary hyperparathyroidism. While surgery represents the mainstay of treatment for both the primary tumour and metastasis, patients no longer amenable to surgical resection often receive unsatisfactory systemic therapies including cinacalcet, adjuvant radiotherapy, and alkylating agents. Given the remarkable results obtained by Lenschow et al. with the anti-PD-1 agent pembrolizumab in the above-mentioned case, we performed an extensive search for possible further relevant data.