Parathyroid cysts: the Latin-American experience

Introduction

Parathyroid cysts are a rare entity. Clinically, they may present as asymptomatic nodules and sometimes may be confused with “thyroid nodules”. Parathyroid cysts must be always considered in the differential diagnosis of anterior neck masses (1). Most of them are non-functional, however 10–15% may secret parathyroid hormone (PTH) (1,2) and demonstrate the clinical manifestations of a primary hyperparathyroidism. Sometimes, parathyroid cysts may resemble giant goiters with extension to the mediastinum compressing the trachea causing obstructive symptoms (2). Treatment options include aspiration, percutaneous sclerosing agents injections or surgical resection (1,3). There are few reports of this disease from Latin America. The cases from Colombia with a review of the cases from Latin America are presented.

Methods

The experience of our centers in the diagnosis and management of parathyroid cyst is presented according to the CARE guidelines for reporting case reports (4), as well as a review of the topic and the cases reported from Latin America based on a search of Medline, Embase, BIREME, LILACS and Scielo databases with the Mesh terms “parathyroid diseases” and “cysts”. Also a search in Google Scholar was performed as well as a review of the references of all original articles and telephonic or email communications with other experts in the field from Latin America. The search was performed in English, Spanish and Portuguese. We found 654 references in Medline, 5 references were found in Scielo, 38 in Google Scholar, 54 in BIREME and 6 in LILACS. Publications of countries outside Latin America were excluded as well as reports about other types of cyst and narrative reviews. The study was approved by ethics committee/ethics board of the Dinámica IPS.

Results

Case presentations from Colombia

During a nine year 9 years period [2005–2014], seven patients with parathyroid cyst were diagnosed and treated. One of the cases is excluded from this report due to incomplete clinical data. The demographic characteristics are presented in Table 1. The first two cases are presented as an example.

Table 1 Clinical characteristics of 18 patients with parathyroid cysts reported in Latin America
Full table

Case 1

Our first patient was a 44-year-old male with past medical history of paranoid schizophrenia and primary hypothyroidism who presents with an anterior neck mass of 1 year of evolution. Computed tomography showed a cystic mass of 10 cm largest diameter, in close contact with left thyroid lobule, extension to superior mediastinum and displacement of common carotid artery and trachea (Figure 1). The patient underwent surgical resection and a parathyroid cyst was confirmed. On hematoxylin-eosin examination, a benign cystic lesion was observed with presence of cuboid epithelial cells and small columnar cell covered with fibrous tissue and parathyroid tissue in the wall of the cyst (Figure 2).

Figure 1 Contrast CT imaging of case 1.

Figure 2 Micrograph of case 1. On hematoxylin eosin examination, a benign cystic lesion was observed with presence of cuboid epithelial cells and small columnar cell covered with fibrous tissue and parathyroid tissue in the wall of the cyst (40×).

A cystic lesion is shown in close contact with left thyroid lobules and displacement of common carotid artery and the trachea.

Case 2

The second case was a healthy 25-year-old woman who presents with a 15-month history of a left par tracheal mass. The ultrasonography examination showed a simple cystic lesion in the left thyroid lobule. A fine needle aspiration was performed with the finding of clear fluid with high PTH levels (300 pg/mL) (Figure 3).

Figure 3 Macroscopic aspect of the fluid of a parathyroid cyst. Clear fluid from parathyroid cyst aspiration with high PTH level (300 pg/mL). PTH, parathyroid hormone.

Cases from Latin America

The search of the literature retrieved 11 references of reported cases from countries of Latin America. The cases found with the relevant findings are presented in Table 1 divided by country of origin of the report.

Discussion

Parathyroid cysts are an uncommon entity in the usual clinical setting (1,14,15). The first description of a parathyroid cyst and parathyroid gland in humans was done in 1880 by the Swedish anatomist Ivar Sandström (16-18), but only in 1905 the first surgical resection was performed by Goris (19) and several years later, Crile in 1953 become the first to diagnose a parathyroid cyst by fine needle aspiration (20). More than 300 hundred cases have been reported since those early studies (3). Parathyroid can be as high as 1.3% to 3% in patients undergoing parathyroidectomy for primary hyperparathyroidism (2,21,22) or as low as 0.075% in unselected patients by ultrasonography (23). There is an increased frequency in older individuals and is more common between fourth and fifth decade (24), however, there are several case reports in children (5,22,25). They are usually found in women, but functional cyst is more frequently found in men (15). The localization is variable between mandible and the mediastinum (3,22). Although parathyroid cysts are usually non-functioning, around 10% may secrete PTH (2) and produce a primary hyperparathyroidism (26-28). This duality suggests differences in the pathogenesis of both types of cysts.

The clinical presentation is highly variable. It can be asymptomatic, present with obstructive symptoms or produce hypercalcemia with its known clinical symptoms. A familial form has been described, familial cystic parathyroid adenomatosis, in which cystic parathyroid adenomas are present in association with maxillary or mandible tumors similar to ossifying fibromas (29). In presence of a cystic mass in the neck in or around the thyroid, a crystal clear fluid in the aspirate should raise suspicion of a parathyroid cyst. A high PTH level in the fluid confirms the diagnosis of parathyroid cyst (30,31). A biochemical evaluation should be completed with parathyroid hormone and calcium in blood to rule out a functional parathyroid cyst. The differential diagnosis is always a cystic nodule of the thyroid.

The treatment of choice is percutaneous aspiration (32,33). Surgical resection should be performed when the parathyroid cyst is functional, in recurrent cases or when obstructive symptoms are present. Other therapeutic options include percutaneous sclerosing agent infusion such as ethanol or tetracycline (34-36). Aspiration has been the main treatment modality in our cases. Two of the cases from Colombia were previously reported (37,38) and during the last 10 years the clinical data of parathyroid cysts in our institutions has been compiled. Currently six cases have been diagnosed and managed and one case with no clinical data was seen from other city, but we believe that there are more cases as this entity is misdiagnosed or the treating physician or the pathologist is not aware of the existence of this disease. A similar situation may be occurring in other countries from Latin America as we only found 11 case reports and not a single review or original article. Most of them were cysts larger than 2 cm and very few had a determination of PTH level in the cyst fluid. Although some of them had obstructive symptoms and a large size, the uncertain diagnosis may be an explanation for the surgical management in almost all cases. This suggest that aspiration of any cyst and PTH measurement in those with a clear crystal fluid may improve the preoperative diagnose and prevent a surgical procedure.

Our study might have not included some cases from our region that may have been missed from our search, as some journals were discontinued, not registered in databases or do not have website or even also by the time the case was reported some new laboratory techniques were not available in Latin-American. This was prevented by a wide search in three languages, a search in Google Scholar and written communication with other colleagues. There is a need for more studies about parathyroid cyst in our region as well as a dedicated registry of this disease. In conclusion, we strongly suggest a PTH determination in a cyst fluid if it is highly characteristic (clear or crystal color) of parathyroid cyst.

Acknowledgements

To the office of Suministro de Documentos de la Biblioteca Médica de la Facultad de Medicina de la Universidad de Antioquia for providing manuscripts of the offline references.

Footnote

Conflicts of Interest: This work was presented partially as an Endocrine Society’s Presidential Poster Competition for first authors during the Annual Meeting & Expo ENDO 2015. San Diego, California. Parathyroid cyst. The Latin America Experience.

Ethical Statement: The study was approved by institutional/regional/national ethics committee/ethics board of Dinámica IPS and written informed consent was obtained from all patients.

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