Large non-functioning parathyroid cysts: our institutional experience of a rare entity and a possible pitfall in thyroid cytology

Parathyroid Cystic Adenoma: A Systematic Review and Meta-Analysis

OBJECTIVE

To review diagnostic imaging modalities for parathyroid cystic adenomas (PCA). Since PCAs are a rare (0.5%-1%) subclass of parathyroid adenomas, and due to their cystic component, imaging modalities known to be efficient for diagnosing solid adenomas might fail in localizing them.

METHODS

We conducted a systematic review using the PubMed and Cochrane databases for English articles on PCAs published between 1995 and 2020. A meta-analysis of the retrieved data was performed.

RESULTS

Overall, 39 studies, reporting on a total of 160 patients, were included in the analysis. Two thirds (68%) of the patients were female, with a mean age of 53.9 years. A single cystic adenoma was detected in 98.1% of cases. The mean blood calcium corrected for albumin level was 12.6 ± 2.7 mg/dL, and the mean parathyroid hormone level was 565.5 ± 523.8 pg/mL. The mean PCA sizes as measured by ultrasound (US), computed tomography (CT), and ex vivo measurement were 4.8 ± 3.6, 5.2 ± 3.2, and 3.5 cm, respectively. The median weight was 8.1 g. PCA was detected in 86% of US examinations; 100% of US-guided fine needle aspiration, 4-dimensional computed tomography (4D-CT), or magnetic resonance imaging examinations; and 61% of 99m-technetium sestamibi scan with single-photon emission computed tomography ((99m)Tc-SPECT). (99m)Tc-SPECT showed a significantly lower diagnostic rate than US (odds ratio, 3.589), US-guided fine needle aspiration, CT combined with 4D-CT, and the combination of US, CT, 4D-CT, and magnetic resonance imaging (P < .001).

CONCLUSION

Although US and 4D-CT showed a significantly high rate in diagnosing PCA, (99m)Tc-SPECT showed a lower PCA diagnostic rate. These findings suggest that larger cystic lesions suspected as PCAs should be further evaluated using 4D-CT rather than (99m)Tc-SPECT.

Intrathyroidal Parathyroid Cyst in a Middle-aged Woman

Parathyroid cyst is a rare entity that can closely mimic thyroid and brachial cleft cysts, particularly when located within the thyroid gland. Most commonly, the cysts are non-functional but can produce compressive symptoms. The cyst contains watery content with elevated PTH levels, specifying parathyroid origin1. Parathyroid cysts should be considered in the differential in patients with a neck mass. This study describes a rare case of a middle-aged woman with a history of a symptomatic intrathyroidal parathyroid cyst discovered intraoperatively.

Parathyroid cyst eclipsed by parathyroid adenoma: Value of adjunct imaging

Parathyroid cyst is a rare clinical entity and often presents as a diagnostic challenge, especially when presents in conjunction with a coexistent parathyroid adenoma. Patient with primary hyperparathyroidism had presented with a localised left inferior parathyroid adenoma with a coexistent right inferior parathyroid cyst which was initially missed on routine ultrasound and sestamibi scan. Suspicion of right inferior thyroid cyst was raised on ultrasound done by a dedicated parathyroid ultrasonologist. Right inferior thyroid cyst was confirmed to be parathyroid cyst on histopathological examination. Parathyroid cysts are seldom picked on sestamibi due to compressed parathyroid tissue present only at the periphery of the cyst. Hence, use of adjunct anatomical imaging like ultrasound, CT scan or MRI is worthwhile to reduce chances of missing hyperfunctional parathyroid tissue, which can eventually lead to revision surgery for persistent primary hyperparathyroidism.

Parathyroid cysts: experience of a rare phenomenon at a single institution

Background

Parathyroid cysts are relatively uncommon lesions and are often misdiagnosed. We evaluate our experience in the diagnosis of and therapy to correct parathyroid cystic lesions.

Methods

We retrospectively reviewed a series of 32 patients with parathyroid cysts who were admitted to our department between July 2011 and November 2016. Clinical pathological features of the patients, including age, gender, location, size, ultrasonography, histopathology, surgery, and follow-up, were analyzed.

Results

There were 22 female and 10 male participants with a median age of 46.7 years old (27–76 years old). Only two cysts were found in the superior mediastinum. The rest were located under the lower pole of the thyroid. All of the patients underwent ultrasonography scans and serum parathyroid hormone (PTH) assays. Three patients had elevated serum PTH levels, and they were further scanned with Tc99m sestamibi as functional cysts. In 29 cases of nonfunctional cysts, 3 cases were preoperatively diagnosed by cystic aspiration with PTH detection. The rest were diagnosed by postoperative immunopathology. All of the patients underwent cystectomy, and 24 patients also underwent thyroidectomy. There was a significant difference in cyst diameter size between the cystectomy alone and cystectomy with thyroidectomy groups (4.0 ± 2.0 vs 1.5 ± 1.0 cm; p < 0.05). No participant experienced recurrence during the median 36 months of follow-up.

Conclusions

Cystic lesions located under the lower pole of the thyroid gland should be considered to have originated at the parathyroid gland. Cystic aspiration with PTH detection or postoperative immunopathology can lead to a definitive diagnosis. Cystectomy is still a commonly used and effective treatment.

Cytomorphologic features distinguishing Bethesda category IV thyroid lesions from parathyroid

Background:

Thyroid follicular cells share similar cytomorphological features with parathyroid. Without a clinical suspicion, the distinction between a thyroid neoplasm and an intrathyroidal parathyroid can be challenging. The aim of this study was to assess the distinguishing cytomorphological features of parathyroid (including intrathyroidal) and Bethesda category IV (Beth-IV) thyroid follicular lesions, which carry a 15%–30% risk of malignancy and are often followed up with surgical resection.

Methods:

A search was performed to identify “parathyroid” diagnoses in parathyroid/thyroid-designated fine-needle aspirations (FNAs) and Beth-IV thyroid FNAs (follicular and Hurthle cell), all with diagnostic confirmation through surgical pathology, immunocytochemical stains, Afirma^® analysis, and/or clinical correlation. Unique cytomorphologic features were scored (0-3) or noted as present versus absent. Statistical analysis was performed using R 3.3.1 software.

Results:

We identified five FNA cases with clinical suspicion of parathyroid neoplasm, hyperthyroidism, or thyroid lesion that had an eventual final diagnosis of the parathyroid lesion (all female; age 20–69 years) and 12 Beth-IV diagnoses (11 female, 1 male; age 13–64 years). The following cytomorphologic features are useful distinguishing features (P value): overall pattern (0.001), single cells (0.001), cell size compared to red blood cell (0.01), nuclear irregularity (0.001), presence of nucleoli (0.001), nuclear-to-cytoplasmic ratio (0.007), and nuclear chromatin quality (0.028).

Conclusions:

There are cytomorphologic features that distinguish Beth-IV thyroid lesions and (intrathyroidal) parathyroid. These features can aid in rendering correct diagnoses and appropriate management.

Fine-Needle Aspiration with Immunohistochemistry Using a Modified Scrape Cell Block Technique for the Diagnosis of Thyroid and Parathyroid Nodules

OBJECTIVE

To evaluate the diagnostic accuracy of a modified scrape cell block (SCB) technique in a large series of patients. The technique was especially developed and tested for fine-needle aspiration of thyroid and parathyroid nodules.

STUDY DESIGN

Eighty-two ultrasound-guided fine-needle aspiration specimens with the sonographic aspect of a thyroid (n = 33) or a possible parathyroid nodule (n = 49) were studied. Immunohistochemistry (IHC) was used on cell blocks containing plasma, thromboplastin, and selected 3-dimensional cell aggregates scraped off Papanicolaou-stained smears. Antibodies for chromogranin A, thyroglobulin, parathyroid hormone, calcitonin, and carcinoembryonic antibody (CEA) were used. In cases of reduced immunosensitivity or suspected metastases or rare primary tumors, additional IHC markers were employed.

RESULTS

Chromogranin A was expressed in all 28 parathyroid adenomas (PA), in 7 of 8 hyperplastic parathyroid glands, and in 13 of 14 medullary thyroid carcinomas (MTC). When combining positivity for chromogranin A and calcitonin/CEA, the specificity for the detection of MTC was 100%. Parathyroid hormone was expressed in 26 of 36 parathyroid nodules (72.2%). When combining follicular microarchitecture and expression of chromogranin A, the specificity for the detection of parathyroid tissue was 97%.

CONCLUSION

With the modified SCB technique, accurate cytological diagnoses were obtained in 97.6% of 82 patients.

Giant non-functional parathyroid cyst: A case report

Giant parathyroid cysts (PCs) are a rare entity and possess a benign clinical course. PCs may be functional or non-functional, depending on the ability of the cyst to secrete parathyroid hormone (PTH). The present study reports a rare case of a giant PC in a 56-year-old male who presented to the Affiliated Tumor Hospital, Zhengzhou University (Zhengzhou, Henan, China) with a 10-month history of exertional dyspnea, associated with mild dysphagia that had persisted for 3 months. The present study reviews the clinical situation, laboratory examination, radiographic findings, treatment and prognosis of the patient, and provides a brief discussion regarding the associated literature. Giant PCs may manifest with compressive symptoms of the surrounding tissues. The diagnosis of a giant PC is based on increased levels of PTH in the fluid collected during the aspiration of the cyst. Management by surgical excision is recommended for giant PCs that cause local cervical symptoms.

An Unusual Neck Mass: A Case of a Parathyroid Cyst and Review of the Literature

Parathyroid cysts (PC) are an unusual cause of neck swellings. The majority are nonfunctioning and prove to be a diagnostic challenge given their nonspecific physical and radiological characteristics. This is compounded by their rare occurrence, leading them to be overlooked in the differential diagnosis of neck lumps. Imaging techniques fail to determine the origin of these lesions, but a preoperative diagnosis can be achieved by fine-needle aspiration and measurement of cystic fluid C-terminal parathyroid hormone levels. Treatment of nonfunctioning cysts remains controversial and includes needle aspiration, injection of sclerosant, or surgical excision. We present a case of a 44-year-old female presenting with an asymptomatic anterior neck swelling, diagnosed postoperatively as a parathyroid cyst.