Parathyroid cancer (PC) is a rare sporadic or hereditary malignancy whose histologic features were redefined with the 2022 WHO classification. A total of 24 Italian institutions designed this multicenter study to specify PC incidence, describe its clinical, functional, and imaging characteristics and improve its differentiation from the atypical parathyroid tumor (APT).
Data were obtained through a form sent to the 24 Italian Institutions part of the IPCSG, collecting all relevant information about PC and APT patients treated between January 1, 2009, and December 31, 2021. Minimum follow-up period was of at least 6 months. The study population consisted of 7857 patients who had undergone parathyroidectomy. Perioperative, pathologic and follow-up variables were obtained for PCs and APTs, which constituted the study groups.
Among 8361 parathyroidectomies, 351 patients (mean age 59.0±14.5; F=210, 59.8%) were divided into the APT (n = 226, 2.8%) and PC group (n=125, 1.5%). PC showed significantly higher rates (p<0.05) of bone involvement, abdominal, and neurological symptoms than APT (48.8% vs. 35.0%, 17.6% vs. 7.1%, 13.6% vs. 5.3%, respectively). Ultrasound (US) diameter >3 cm (30.9% vs. 19.3%, p = 0.049) was significantly more common in the PC. A significantly higher frequency of local recurrences was observed in the PC (8.0% vs. 2.7%, p =0.022). Mortality due to consequences of cancer or uncontrolled hyperparathyroidism was 3.3%.
Symptomatic hyperparathyroidism, high PTH and albumin-corrected serum calcium values, and a US diameter >3 cm may be considered features differentiating PC from APT. WHO 2022 criteria did not impact the diagnosis.