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Parathyroid cyst

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									奇美




     Parathyroid Cyst

       Chi Mei Medical Center
           Hon Mei Cheng
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                    Case Report
     • 54 y/o F, neck mass noted for more than 10 years,
       thyroid cyst was told, aspiration was frequently
       performed.
     • 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
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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
       extirpation.
     • 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
       disease.
     • 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
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     • 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
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             Coalescent parathyroid cysts
 • Thought to form from the "coalescence of microcysts"
   within an otherwise normal parathyroid gland or an
   adenoma.
 • 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
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              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
  fluid.
• 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
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                      Diagnosis
     • Needle aspiration biopsy of the thyroid and
       parathyroid.
     • Aspiration biopsy is the most definitive diagnostic
       step in the investigation of thyroid and parathyroid
       masses.
     • 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
   sclerotherapy.
 • Surgical removal should be considered for parathyroid cysts
   that are (1) refractory to aspiration or sclerotherapy, (2)
   nonfunctional but symptomatic, or (3) hyperfunctional.
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     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
       swellings.
     • 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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