Unusual presentations of functional parathyroid cysts: a case series and review of the literature

El-Housseini et al. Journal of Medical Case Reports (2017) 11:333 DOI 10.1186/s13256-017-1502-1 CASE REPORT Open Access Unusual presentations of functional parathyroid cysts: a case series and review of the literature Youssef El-Housseini1, Martin Hübner2, Ariane Boubaker3, Jan Bruegger1, Maurice Matter2† and Olivier Bonny1*† Abstract Background: Cysts of parathyroid origin are sometimes encountered and can easily be mistaken as thyroidal cysts. Functional parathyroid cysts, with symptoms and signs of hyperparathyroidism, are rare and may be a diagnostic challenge to clinicians. We report here on three cases of functional parathyroid cysts that illustrate diagnosis difficulties related to unusual clinical presentations in three Caucasian women, including negative parathyroid scintigraphy. Case presentations: Patient 1, an 87-year-old Caucasian woman presented with confusion and dysphagia. She had hypercalcemia and elevated parathyroid hormone levels suggesting primary hyperparathyroidism. Parathyroid scintigraphy did not reveal any focal uptake, but a computed tomography scan of her neck identified a large cyst in the upper right thyroid region. At cervicotomy, a parathyroid cystic adenoma was removed. Patient 2, a 31-year-old Caucasian woman was investigated after a hypertensive crisis related to primary hyperparathyroidism. Cervical ultrasound identified a large cystic lesion in the lower left thyroid lobe that was removed by minimally invasive cervicotomy. Patient 3, a 34-year-old Caucasian woman presented with an indolent growing mass of the neck and a past medical history of kidney stones. Primary hyperparathyroidism was diagnosed. Ultrasound showed a cystic mass, but parathyroid scintigraphy was negative. Cervical exploration revealed a large cystic adenoma, containing high parathyroid hormone levels. Conclusions: Diagnosis of functional parathyroid cysts can be challenging due to various clinical presentations and negative parathyroid scintigraphy. Surgery, but not fine-needle sclerotherapy, appears to be the safest treatment option. Despite its rarity, differential diagnosis of cystic lesion of the neck should include primary hyperparathyroidism due to functional parathyroid cysts. Keywords: Hyperparathyroidism, Parathyroid cyst, PTH, Parathyroid hormone, Case report Background Cysts of the parathyroid gland are traditionally classified as either non-functional or as functional and may represent up to 5% of all cystic tumors of the anterior neck [1]. The majority of parathyroid cysts are non-functional, generally discovered during thyroid or cervical investigations, and are not associated with primary hyperparathyroidism [2]. By contrast, functional cysts induce symptoms and signs of primary hyperparathyroidism. Their fluid contains * Correspondence: † Equal contributors 1 Service of Nephrology and Hypertension, Lausanne University Hospital, Rue du Bugnon 17, 1011 Lausanne, Switzerland Full list of author information is available at the end of the article high concentrations of parathyroid hormone (PTH), which may induce parathyroid crisis in case of rupture. Here, we report three cases of patients with functional parathyroid cysts, with atypical presentation, and we propose a simple investigation and treatment algorithm. 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) © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. El-Housseini et al. Journal of Medical Case Reports (2017) 11:333 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 (Fig. 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 Page 2 of 8 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 (Fig. 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. 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 (Fig. 2a). A left lo (...truncated)