Immunohistochemical Expression of E-Cadherin in Atypical Parathyroid Adenoma.

Background: Atypical parathyroid adenoma (APA) is a rare entity, sharing clinical symptoms like solid palpable mass in the neck, laboratory changes with very high serum calcium and parathyroid hormone levels, and some histopathological features with parathyroid carcinomas (PC). However, clinical behavior of APA seems to comply with benign parathyroid tumors (PA). There is some evidence that loss of the membranous staining pattern of E-Cadherin (E-Cad) suggests a key role of epithelial mesenchymal transition in the tumorigenesis of PC.