A giant parathyroid adenoma weighs more than 3.5 g and is more than 2cm in size.
This case report describes primary parathyroid adenoma and although the initial assessment was of thyroid origin, it was later diagnosed to be of parathyroid origin.
Case Report
A 48-year-old Persian man from Urmia, Iran, arrived at Imam Hospital complaining of dizziness, fatigue, knee pain, and lower back pain, for the past two months. The patient had a 30-year history of mitral valve replacement, several bilateral nephrolithotripsies, and diabetes mellitus, which was controlled with oral medication. Moreover, his vital signs were normal. There was a large and soft nodule in his thyroid’s left lobe that moved when he swallowed. A scar from previous cardiac surgery was visible on the chest. However, the rest of his examination was normal.
Doctors did a colour Doppler ultrasonography of his thyroid and parathyroid. It revealed a single isoechoic nodule in the right lobe and two cystic nodules in the left lobe. However, as opposed to the patient’s biochemistry, a cystic mass in the left lobe of the thyroid was visible on computed tomography, which indicated parathyroid carcinoma. Moreover, the findings were validated using 99mTc-MIBI scintigraphy. His complete blood count was normal. The serum calcium and PTH levels were 14.6 mg/dL and 2702 pg/mL, respectively. Furthermore, urine analysis revealed trace proteinuria, with two to three RBCs per high-power field.
The possibility of a parathyroid adenoma was high enough. It was based on the patient’s lab and imaging findings to send the patient to surgery for removing the tumour.
Treatment
The surgery was performed under general anaesthesia. Subplatysmal flaps were created as part of a routine thyroidectomy procedure after a large collar incision was made. Approximately two fingers width above the suprasternal notch. Moreover, the raphe between the strap muscles was opened, and the muscles were incised on the left near the upper pole of the thyroid.
Initially, it appeared as a thyroid mass that was only displacing the carotid sheath laterally. Other than that, it was also extending into the mediastinum as a retrosternal goitre after the thyroid was exposed. Moreover, examination revealed a central posterior neck mass with mediastinum extension that displaced the carotid sheath laterally and the left lobe of the thyroid superior and medially. The inferior thyroidal artery passed through the mass and into the carotid sheath. These results pointed to a parathyroid origin, most likely from the superior parathyroid glands. The inferior thyroid artery was ligated as laterally as possible, the tumour’s lateral side was dissected out with sharp and blunt dissection, and the tumour was pulled out of the mediastinum and into the neck.
Final Diagnosis: Parathyroid Adenoma
The patient was diagnosed with parathyroid carcinoma based on the PTH value, tumour size, and adhesion to adjacent tissues, and the tumour, right lobe of the thyroid, and adjacent lymph nodes were resected. Furthermore, the neck wound was closed after a Hemovac drain was inserted. The doctors believe that the mass originated from the superior parathyroid gland because it descended to the retro-oesophagal space and was located posterior to the recurrent laryngeal nerve.
Recovery and Follow-Up
The recovery period was uneventful. To prevent bone hunger syndrome, an intravenous infusion of calcium gluconate was administered within the first 24 hours. Moreover, the patient was discharged on the third postoperative day with oral CaCO3 and calcitriol pearls that were gradually tapered until they were discontinued after two weeks.
The resected mass was histopathologically determined to have a parathyroid adenoma and a multinodular goitre of the resected thyroid lobe. Histopathological examination revealed no lymph node or local invasion, vascular invasion, or perineural invasion. Furthermore, there was no significant invasion of adjacent structures or organs either. The patient was followed for a year without incident.
