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Parathyroid cyst



     Parathyroid Cyst

       Chi Mei Medical Center
           Hon Mei Cheng

                    Case Report
     • 54 y/o F, neck mass noted for more than 10 years,
       thyroid cyst was told, aspiration was frequently
     • 10-20 cc clear, colorless, watery fluid from left
       lower portion of thyroid lobe.
     • FNA: negative, only RBCs and a few leukocytes.
       No epithelial cells are identified.
     • PTH assay: iPTH 131.8 pg/mL (14 -72)
     • TFT: T4 3.90 ug/dL; TSH3.08 uIU/mL
奇美                  Parathyroid cyst
     • Sandström (1880) is generally credited with describing
       the first macroscopic parathyroid cyst.
     • Goris (1905) was the first to describe its surgical
     • Parathyroid cysts are rare. As of 1996, 200 reported
       cases in the literature.
     • Exact incidence of parathyroid cysts is debatable,
       0.08% to 3.4% resections of thyroid or parathyroid
     • In 1 study of all thyroid and parathyroid specimens
       examined over a 15-year period, parathyroid cysts were
       found in 0.6% of the specimens.
                                          Arch Otolaryngol Head Neck Surg
                                                2002; 128(5):592-594

     • Parathyroid cysts may present as an asymptomatic
       neck mass or with symptoms associated with
       compression of adjacent structures, such as
       dysphagia, dyspnea, or even hoarseness.
     • Typically arising from the inferior parathyroid gland.
     • Often they are discovered as incidental surgical or
       radiological findings.
     • Parathyroid cysts may be functional (eg, causing
       hyperparathyroidism) or nonfunctional.
     • Nonfunctional cyst is more common, but functional
       cysts may be found.
                                       Arch Otolaryngol Head Neck Surg
                                             2002; 128(5):592-594
奇美            Classification of parathyroid cysts
               Ontogenous parathyroid cyst
     • Develops from vestigial remnants of the third or
       fourth branchial clefts.
     • Typically an encapsulated, thin-walled cyst containing
       clear fluid. The cyst is lined by a single layer of
       parathyroid cells may secrete parathyroid hormone,
       which can be measured in the cyst fluid.
     • Derived from the lining cells of canals of Kürsteiner,
       the embryonic ducts that connect thymic and
       parathyroid primordia of branchial pouches 3 and 4
       during development.
     • The lining cells may form islands of parathyroid
       tissue in the cyst wall, which in rare cases may
       undergo adenomatous change, resulting in primary
       hyperparathyroidism.                 Mallette LE. The Parathyroids
             Coalescent parathyroid cysts
 • Thought to form from the "coalescence of microcysts"
   within an otherwise normal parathyroid gland or an
 • Alternatively, cysts form from the rapid enlargement of
   a single microcyst within the gland.
 • Cyst may contain serous or serosanguineous fluid.
 • Rather than having a single cell layer, the cyst is lined by
   a layer of parathyroid cells that is several cells thick.
 • When cyst arises in an adenoma, the patient may
   develop hyperparathyroidism. When cyst arises in a
   normal gland, the patient is usually normocalcemic.
                                 Mallette LE. The Parathyroids
                             New York, NY: Raven Press; 1994:423-455

              Parathyroid pseudocyst

• The third and final type is parathyroid pseudocyst.
• In this type, cyst formation is due to infarction and
  degeneration of an adenoma.
• Pseudocysts are usually filled with a turbid, reddish brown
• The pseudocyst wall is typically thick and fibrotic, with
  entrapped residual parathyroid tissue.

                              Mallette LE. The Parathyroids
                              New York, NY: Raven Press; 1994:423-455

     • Needle aspiration biopsy of the thyroid and
     • Aspiration biopsy is the most definitive diagnostic
       step in the investigation of thyroid and parathyroid
     • The clear fluid from the rare parathyroid cyst
       should be sent for parathyroid hormone assay.

                             Otolaryngologic Clinics of North America
                                    23(2):217-29, 1990 Apr
奇美                     Treatment
 • Primary treatment for parathyroid cysts is surgical removal.
 • Some authors have advocated repeated aspiration and even
   sclerotherapy for nonfunctioning parathyroid cysts.
 • Of 4 patients treated with tetracycline sclerotherapy in 1
   study, only 2 were without evidence of disease at follow-up
   of 12 to 54 months.
 • One patient retained a small, asymptomatic cyst. Another
   required a second course of sclerotherapy 7 months after
   the initial treatment.
 • Parathyroid cysts can persist or recur after aspiration and
 • Surgical removal should be considered for parathyroid cysts
   that are (1) refractory to aspiration or sclerotherapy, (2)
   nonfunctional but symptomatic, or (3) hyperfunctional.

     Giant mediastinal parathyroid cyst
     • Cysts of the parathyroid gland located in the
       mediastinum are rare but well-defined clinical and
       pathologic entities.
     • Since the first case report in 1925 a total of 28
       mediastinal parathyroid cysts have been reported.
     • An 83-year-old woman had a giant mediastinal
       parathyroid cyst with acute hypercalcemic crisis is
       reported, symptoms resolved completely after the
       cystic tumor was resected.

                                   Surgery 120(5):795-800, 1996 Nov
奇美                       Conclusion
     • Parathyroid cysts are rare, representing 1% of all neck
     • A correct preoperative diagnosis is rarely formulated,
       especially because of the non-specific clinical and
       ultrasonographic findings.
     • Patients are often submitted to surgery for thyroid nodules.
     • Preoperative diagnosis was correctly formulated following the
       aspiration and PTH assay of clear, watery fluid from the cyst.
     • While cyst aspiration is considered the elective treatment for
       these lesions, recurrences being uncommon
     • Surgery was indicated for recurrences after aspiration and the
       onset of compressive symptoms.
     • Cystic masses of the neck should be accurately diagnosed to
       recognize their true nature and to allow their correct and non-
       invasive treatment
                                                    Journal of Laryngology & Otology
                                                        113(1):73-5, 1999 Jan

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