1. Introduction
Parathyroid glands normally descend from their embryologic origin in the
pharyngeal pouches to their final locations in the central neck.
However, aberrant migrations can lead to one or more parathyroid glands
being in non-anatomic locations, including retroesophageal space,
thymus, mediastinum, or within the thyroid gland. Rarely they fail to
migrate, resulting in an undescended gland. Adenomas arising from these
locations should be considered when initial preoperative imaging fails
to identify a target adenoma or after unsuccessful surgery. Here we
present a case of an ectopic parathyroid adenoma arising at the level of
the pyriform sinus.