Unusual Presentations of Functional Parathyroid Cysts

A Case Series and Review of the Literature

Youssef El-Housseini; Martin Hübner; Ariane Boubaker; Jan Bruegger; Maurice Matter; Olivier Bonny


J Med Case Reports. 2017;11(333) 

In This Article

Case Presentation

We reviewed 10 years of activity (2002 to 2012) of parathyroid surgery at our university hospital, a tertiary referral center for endocrine surgery. The rationale for the starting point was the standardization of diagnostic work-up and surgical technique in 2002: systematic double-phase parathyroid scintigraphy with technetium 99 m (99mTc)-sesta methoxyisobutylisonitrile (sestamibi) for primary hyperparathyroidism and introduction of minimally invasive focused surgery. During this time period, 187 patients underwent parathyroidectomy for primary hyperparathyroidism and 32 patients for secondary or tertiary hyperparathyroidism. Three patients with parathyroid cysts were identified during this period (1.4% of all cases of operated hyperparathyroidism).

Case 1

An 87-year-old Caucasian woman presented to our emergency room with a 10-day history of progressive mental confusion and dysphagia. On admission, her blood pressure (BP) was 107/72 mmHg, pulse rate 80 beats/minute, and temperature was 36.5 °C. She was disoriented and dehydrated. Blood tests revealed hypercalcemia (13.8 mg/dl; normal range, 8.6 to 10.2 mg/dl), elevated PTH levels (305 pg/ml; normal range, 10 to 70 pg/ml), and concomitant low levels of 25-hydroxyvitamin D (25-OH vitamin D). Her renal function was impaired with estimated glomerular filtration rate (GFR) at 36 ml/minute per 1.73 m2. A cervical computed tomography (CT) scan (Figure 1a and Table 1) identified a right-sided cystic nodule. Double-phase parathyroid scintigraphy with single-photon emission CT (SPECT)-CT was negative. Hypercalcemia improved with pamidronate treatment, but her plasma PTH remained high despite vitamin D supplementation. During cervicotomy, three normal-sized parathyroid glands were detected (upper and lower left and lower right), and confirmed by frozen sections. Deep behind her right inferior thyroid artery, a 3.5 × 3 × 2 cm cystic tumor filled with colloid-like fluid was carefully removed (Figure 1b). Histopathological analysis confirmed a parathyroid adenoma with cystic transformation. She developed transient postoperative hypocalcemia, requiring calcium and 1,25-dihydroxyvitamin D3 (1,25-(OH)2 vitamin D3) substitution. Normalization of calcium and PTH levels was associated with full recovery, including normal mental status. At 6 months, she was fully active and had recovered from renal insufficiency.

Figure 1.

Patient 1. a Cervical computed tomography scan showing a paratracheal and paraesophageal cystic tumor with compression of the esophagus causing dysphagia (arrow). b Intraoperative view of the parathyroid cyst of patient 1 (panels 1 and 2). The cyst is located to the inferior thyroid artery and the laryngeal nerve. Right thyroid lobe is retracted to the left. Panels 3 and 4 Resected cyst with fine lining of parathyroid tissue

Case 2

A previously healthy 31-year-old Caucasian woman was investigated after acute transient ischemic attack attributed to a hypertensive crisis. Investigations excluded renovascular or adrenal causes for her hypertension. However, hypercalcemia and raised PTH levels (169 pg/ml; normal value, 10 to 70 pg/ml) suggested a diagnosis of hyperparathyroidism. A cervical ultrasound (US) showed an isolated 2 cm mixed solid and cystic nodule. Double-phase parathyroid scintigraphy with SPECT-CT revealed a lower left focal uptake and 99mTc-sestamibi retention consistent with an adenoma (Figure 2a). A left lower parathyroidectomy was successfully performed through a minimally invasive focused cervicotomy and intraoperative PTH levels went back to normal values within 15 minutes after cyst removal. At 2-week follow-up, her calcium levels and BP had returned to normal ranges. Histopathological analysis showed parathyroid adenoma with cystic transformation, surrounded by thymic tissue composed of pseudocysts lined with parathyroid cells. Six months later, she had fully recovered.

Figure 2.

Patient 2. a Technetium 99 m sesta methoxyisobutylisonitrile scintigraphy (planar and single-photon emission computed tomography-computed tomography) showing a focal tracer retention localized under the left lower thyroid lobe just above the manubrium and anterior to the trachea (red arrows). b Cervical ultrasound with longitudinal view of a mixed solid and cystic nodule

Case 3

A 34-year-old Caucasian woman who was obese, smoked tobacco, hypertensive, and diabetic underwent ambulatory work-up for bilateral kidney stones. She was treated by candesartan 8 mg daily, gliclazide 30 mg daily, and combined metformin 1000 mg/sitagliptin 50 mg twice a day. She also complained of a rapidly growing mass in the left side of her neck. A physical examination showed obesity with a body mass index (BMI) of 32 kg/m2 and revealed a soft and mobile mass on the left side of her neck. Her BP was 132/88 mmHg and heart rate was 98 beats/minute. Her initial PTH level was 557 pg/ml (normal value 10 to 70 pg/ml) and plasma calcium was 11 mg/dl. Despite correction of low 25-OH vitamin D levels, her PTH had increased to 1410 pg/ml 2 months later. A cervical US identified a nodular and multicystic tumor embedded in her left thyroid lobe (Figure 3a). Double-phase parathyroid scintigraphy with SPECT-CT and thyroid scintigraphy showed homogenous thyroid uptake, but identified a hollow zone with a rim of tracer uptake under her left thyroid lobe (Figure 3b), suggesting the presence of a large parathyroid cyst. US-guided puncture of the cyst revealed a PTH concentration of 4,347,000 pg/ml in the fluid, and normal thyroid hormone levels. During cervicotomy, a large left thyroid lobe with mediastinal extension was discovered and an en bloc left thyroidectomy (Figure 3c) was performed, with uneventful recovery. Histopathological examination showed a 5 × 4.5 × 4 cm large cyst lined by parathyroid cells and normal thyroid gland. At 6-month follow-up, she had normal PTH and plasma calcium levels.

Figure 3.

Patient 3. a Cervical ultrasound and longitudinal view of a large cyst. b Technetium 99 m sesta methoxyisobutylisonitrile scintigraphy with single-photon emission computed tomography-computed tomography. A central "cold" area (white arrow) corresponding to the parathyroid cyst is surrounded by faint tracer retention (red arrows) corresponding to the displaced parathyroid parenchyma. c Left thyroid lobe en bloc with the parathyroid cyst. A Cyst, B upper part of otherwise normal looking thyroid gland, C isthmus, D thymic remnant