Parathyroid Crisis as Presentation of Atypical Parathyroid Adenoma: Two Diagnostically Challenging Cases.

Atypical parathyroid adenoma (APA) is a rare cause of primary hyperparathyroidism (PHPT) and represents a diagnostic challenge since it is an intermediate form of parathyroid neoplasm of uncertain malignant potential with atypical histological features that require differential diagnosis of parathyroid carcinoma (PC). We present 2 cases of parathyroid crisis as a presentation of APA. The first case was that of a 56-year-old man with parathyroid crisis, constitutional syndrome, and anemia, with evidence of APA after en bloc resection, evolving with hungry bone syndrome after surgery and curation criteria at 6 months after parathyroidectomy (PTX).