Multicenter Study of 19 Aortopulmonary Window parathyroid Tumors : The callenge of Embryologic origin

Background Ectopic abnormal parathyroid glands are relatively
common in the superior mediastinum but are rarely
situated in the aortopulmonary window (APW). The embryological
origin of these abnormal parathyroid glands is controversial.
The purpose of this investigation was to investigate
the embryological origin and the surgical management of
abnormal parathyroid glands situated in the APW.
Methods The databases of patients operated on for primary,
secondary, and tertiary hyperparathyroidism at eight
European medical centers with a special interest in endocrine
surgery were reviewed to identify those with APW adenomas.
Demographic features, localization procedures, and
perioperative and pathology findings were documented. The
embryological origin was determined based on the number
and position of identified parathyroid glands.
Results Nineteen (0.24%) APW parathyroid tumors were
identified in 7,869 patients who underwent an operation for
hyperparathyroidism (HPT) and 181 patients (2.3%) with
mediastinal abnormal parathyroid glands. Ten patients had
primary, eight had secondary, and one had tertiary HPT.
Sixteen patients had undergone previous unsuccessful cervical
exploration. In three patients, an APW adenoma was
suspected by preoperative localization studies and was cured
at the initial operation. Sixteen patients had persistent HPTof
whom 15 were reoperated, resulting in 6 failures. Evaluation
of 17 patients who had bilateral neck exploration allowed us
to determine the most probable origin of the APW parathyroid
tumors: 12 were supernumerary, 4 appeared to originate
from a superior, and 1 from an inferior gland.
Conclusions Abnormal parathyroid glands situated in the
APW are rare and usually identified after an unsuccessful
cervical exploration. Preoperative imaging of the mediastinum
and neck are essential. The origin of these ectopically
situated tumors is probably, as suggested by our data, from a
supernumerary fifth parathyroid gland or from abnormal
migration of a superior parathyroid gland during the
embryologic development.