Ectopic PTH-producing parathyroid cyst inside the thymus: a case report.

BACKGROUND: The hallmark of hyperparathyroidism is hypersecretion of parathyroid hormone (PTH) which results in hypercalcemia and hypophosphatemia. While hypercalcemia due to malignancy is often brought about by PTH-related protein in adults, PTH-producing tumors are quite rare in clinical practice. Additionally, from the point of embryology, it is very difficult to examine ectopic PTH-producing tissue such as ectopic parathyroid glands. Furthermore, clear histopathological criteria are not present. CASE PRESENTATION: A 57-year-old woman was referred to our hospital for hypercalcemia. Her parathyroid hormone (PTH) level was elevated, but there were no enlarged parathyroid glands. Although 99mTc-MIBI confirmed a localized and slightly hyperfunctioning parathyroid tissue in the anterior mediastinum, it was not typical as hyperfunctioning parathyroid. We finally diagnosed her as ectopic PTH-producing cyst-like tumor with venous sampling of PTH. She underwent anterosuperior mediastinal ectopic PTH-producing cyst-like tumor resection. It is noted that intact-PTH concentration of the fluid in the cyst was very high (19,960,000 pg/mL). Based on histopathological findings, we finally diagnosed her as ectopic PTH-producing parathyroid cyst inside the thymus. After resection of anterosuperior mediastinal thymus including ectopic PTH-producing parathyroid cyst, calcium and intact-PTH levels were decreased, and this patient was discharged without any sequelae. CONCLUSIONS: We should know the possibility of superior mediastinal ectopic PTH-producing parathyroid cyst inside the thymus among subjects with ectopic PTH-producing parathyroid glands. Particularly when the cyst is present in the superior mediastinum, it is necessary to do careful diagnosis based on not only positive but also negative findings in 99mTc-MIBI. It is noted that the patient's bloody fluid in the cyst contained 19,960,000 pg/mL of intact-PTH, and its overflow into blood stream resulted in hyperparathyroidism and hypercalcemia. Moreover, in such cases, the diagnosis is usually confirmed after through histological examination of ectopic PTH-producing parathyroid glands. We think that it is very meaningful to let clinicians know this case.

[Ectopic hyperparathyroidism. Detection of mediastinal localization]. / Hiperparatiroidismo ectópico. Detección de la localización mediastinal.

The ectopic parathyroid tissue is a frequent cause of recurrent hyperparathyroidism (HPT), accounting 16% in primary HPT and 14% in secondary cases. Although intrathoracic ectopic glands represent 25-35% of all ectopic cases, only 2% requires thoracic surgery. The aim of this study is to report a case series of patients with ectopic mediastinal HPT treated by thoracic approach in a private institution in Argentina. This is a retrospective analysis from January 2006 to June 2019. All patients diagnosed with ectopic hyperparathyroidism who required a thoracic surgical approach were included. During this period, 728 patients with primary HPT and secondary HPT were treated. Six with primary HPT and 3 with secondary HPT required a thoracic approach. Six video-assisted thoracoscopy surgeries (VATS) and 3 sternotomies were performed. None of them presented serious posoperative complications. Frozen section biopsy was used in all cases. iPTH was measured in 8 cases, with a mean drop of 65% after 15 minutes. Final pathology reports confirmed 5 adenomas and 4 hyperplasias. Our case series reported an incidence of 1.65% (12/728) mediastinal parathyroids, while 1.24% (9/728) received surgical treatment at our institution. Intraoperative frozen section and PTHi are useful to confirm the diagnosis and to avoid recurrences. Although VATS is a safe and efficient treatment option, it depends on surgical training and availability. In terms of diagnostic imaging resources, sestamibi remains the current gold standard. However, 18F-choline PET/CT may arise as a new diagnostic tool. The possibility of obtaining evidence-based conclusions requires studies with higher number of patients.

El tejido paratiroideo ectópico es una causa frecuente de recurrencia del hiperparatiroidismo (HPT) siendo de 16% en primarios y 14% en secundarios. La localización intratorácica representa el 20-35%, pero solo un 2% requiere una cirugía torácica. El objetivo fue analizar una cohorte de pacientes con diagnóstico de HPT mediastinal operados en un hospital de alta complejidad de Argentina. Se realizó un estudio retrospectivo de todos los operados por HPT entre enero de 2006 y julio 2019 en ese hospital. Se incluyeron aquellos que requirieron acceso torácico por HPT ectópico. En este período se trataron 728 pacientes con HPT primario y secundario. Seis con primario y 3 con secundario requirieron cirugía torácica. Se realizaron 6 videotoracoscopias (VATS) y 3 esternotomías, sin complicaciones graves. Se utilizó biopsia por congelación en todos y dosaje de paratohormona intraoperatoria (PTHi) en 8 casos, que descendió en promedio 65% respecto al valor basal. Se confirmaron 5 adenomas y 4 hiperplasias. La enfermedad paratiroi dea mediastinal representó el 1.65% (12/728), mientras que recibieron tratamiento quirúrgico en nuestra institución 1.24% (9/728). La biopsia por congelación y el descenso de PTHi resultan útiles para confirmar el foco y eventualmente disminuir el riesgo de recurrencia. La VATS es segura pero depende del entrenamiento y de la disponibilidad en el medio asistencial. Si bien el sestamibi es el método con mayor sensibilidad, se propone el uso de 18F-colina PET/TC ante la sospecha de HPT ectópico. La posibilidad de obtener conclusiones basadas en la evidencia requiere de estudios con mayor número de pacientes.

Hiperparatiroidismo ectópico: Detección de la localización mediastinal / Ectopic hyperparathyroidism. Detection of mediastinal localization

El tejido paratiroideo ectópico es una causa frecuente de recurrencia del hiperparatiroidismo (HPT) siendo de 16% en primarios y 14% en secundarios. La localización intratorácica representa el 20-35%, pero solo un 2% requiere una cirugía torácica. El objetivo fue analizar una cohorte de pacientes con diagnóstico de HPT mediastinal operados en un hospital de alta complejidad de Argentina. Se realizó un estudio retrospectivo de todos los operados por HPT entre enero de 2006 y julio 2019 en ese hospital. Se incluyeron aquellos que requirieron acceso torácico por HPT ectópico. En este período se trataron 728 pacientes con HPT primario y secundario. Seis con primario y 3 con secundario requirieron cirugía torácica. Se realizaron 6 videotoracoscopias (VATS) y 3 esternotomías, sin complicaciones graves. Se utilizó biopsia por congelación en todos y dosaje de paratohormona intraoperatoria (PTHi) en 8 casos, que descendió en promedio 65% respecto al valor basal. Se confirmaron 5 adenomas y 4 hiperplasias. La enfermedad paratiroi dea mediastinal representó el 1.65% (12/728), mientras que recibieron tratamiento quirúrgico en nuestra institución 1.24% (9/728). La biopsia por congelación y el descenso de PTHi resultan útiles para confirmar el foco y eventualmente disminuir el riesgo de recurrencia. La VATS es segura pero depende del entrenamiento y de la disponibilidad en el medio asistencial. Si bien el sestamibi es el método con mayor sensibilidad, se propone el uso de 18F-colina PET/TC ante la sospecha de HPT ectópico. La posibilidad de obtener conclusiones basadas en la evidencia requiere de estudios con mayor número de pacientes.

The ectopic parathyroid tissue is a frequent cause of recurrent hyperparathyroidism (HPT), accounting 16% in primary HPT and 14% in secondary cases. Although intrathoracic ectopic glands represent 25-35% of all ectopic cases, only 2% requires thoracic surgery. The aim of this study is to report a case series of patients with ectopic mediastinal HPT treated by thoracic approach in a private institution in Argentina. This is a retrospective analysis from January 2006 to June 2019. All patients diagnosed with ectopic hyperparathyroidism who required a thoracic surgical approach were included. During this period, 728 patients with primary HPT and secondary HPT were treated. Six with primary HPT and 3 with secondary HPT required a thoracic approach. Six video-assisted thoracoscopy surgeries (VATS) and 3 sternotomies were performed. None of them presented serious posoperative complications. Frozen section biopsy was used in all cases. iPTH was measured in 8 cases, with a mean drop of 65% after 15 minutes. Final pathology reports confirmed 5 adenomas and 4 hyperplasias. Our case series reported an incidence of 1.65% (12/728) mediastinal parathyroids, while 1.24% (9/728) received surgical treatment at our institution. Intraoperative frozen section and PTHi are useful to confirm the diagnosis and to avoid recurrences. Although VATS is a safe and efficient treatment option, it depends on surgical training and availability. In terms of diagnostic imaging resources, sestamibi remains the current gold standard. However, 18F-choline PET/CT may arise as a new diagnostic tool. The possibility of obtaining evidence-based conclusions requires studies with higher number of patients.

Parathyroid ectopia: development of a surgical algorithm based on operative findings.

OBJECTIVES: To study the incidence of ectopic parathyroid adenomata from a single surgical series, and to devise a surgical algorithm from the results to follow when an adenoma cannot initially be located. METHODS: A retrospective review was conducted of prospectively collected data. The study comprised all patients who underwent parathyroidectomy between June 2001 and February 2008 under the care of the senior author. A systematic surgical protocol was developed for locating ectopic superior and inferior parathyroid adenomata based on the order of incidence identified from the database. RESULTS: Parathyroid ectopia occurs in approximately 10 per cent of hyperparathyroidism cases. It is more common in superior than inferior parathyroid glands. The most common superior location is the right retroesophageal position and the most common inferior location is within the left thymic remnant. CONCLUSION: Prospective data collection and subsequent analysis can be used to develop a systematic surgical protocol to aid the localisation of ectopic enlarged parathyroid glands in the surgical management of hyperparathyroidism.