Parathyroid gland
Neoplasms
Parathyroid carcinoma

Author: Monika Roychowdhury, M.D. (see Authors page)

Revised: 12 April 2018, last major update January 2013

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Parathyroid carcinoma[TI] free full text[sb]

Cite this page: Roychowdhury, M. Parathyroid carcinoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/parathyroidpthca.html. Accessed August 16th, 2018.
Definition / general
  • Somewhat rare - accounts for less than 1% of all cases of primary hyperparathyroidism (J Cancer 2011;2:532)
  • Usually detected because of palpable neck mass (75%), excessive PTH secretion, high serum calcium (> 14 mg/dl, may recur after surgery) and clinical effects of hypercalcemia (skeletal disease: 73%, renal disease: 26%), vocal cord paralysis
  • Present in 15% with hyperparathyroidism jaw tumor (HPT-JT) syndrome, a rare autosomal disorder (Semin Oncol 2010;37:580)
  • Equal male and female incidence
  • Nonfunctioning tumors are rare (Am J Surg Pathol 1983;7:535)
  • Rarely coexists with adenoma and hyperplasia (Arch Pathol Lab Med 1983;107:349)
  • 1/3 recur locally; 1/3 have distant metastases
  • 79% die of disease after multiple recurrences with repeated resections; 5 year survival 50% (Hum Pathol 2003;34:54)
  • Types: chief cell (functional tumors that present with high serum calcium, 50% die of disease), oxyphil (rare, similar characteristics as chief cell carcinomas; higher Ki67 and lower p27 than oxyphil adenomas, CK14- [usually expressed in oxyphil adenomas, Am J Surg Pathol 2002;26:344], abundant cytoplasmic mitochondria on EM)
  • No current staging for parathyroid carcinomas exists
Diagnosis
  • Based on local invasion and metastases (clinical criteria, NOT microscopic criteria)
  • Higher serum PTH and calcium levels than in parathyroid benign disease may be useful in diagnosis; PTH levels higher than 300 pg/ml are indicator of potential malignant disease (J Cancer 2011;2:532)
Prognostic factors
  • Macronucleoli, more than 5 mitoses per 50 high power fields and necrosis were associated with recurrent disease (Am J Surg Pathol 1993;17:820)
Case reports
Treatment
  • Excise tumor, soft tissue and ipsilateral thyroid lobe
  • Can excise isolated metastases
  • Postoperative radiation to prevent local recurrence
Gross description
  • May be circumscribed
  • Gray-white, firm, irregular, may exceed 10 g, may adhere to adjacent structures, rarely within thyroid gland (Mod Pathol 1989;2:652)
Gross images

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Note large size and irregular cut surface

Cystic mass against thyroid lobe

Microscopic (histologic) description
  • Uniform cells with minimal atypia in nodular or trabecular patterns with dense fibrous bands
  • Tumor cells are spindled, mitotic figures are frequent, atypical mitotic figures relatively specific, capsular invasion present (tongue-like protrusion of tumor cells through capsule) but usually NOT diagnostic because it may be due to prior hemorrhage
  • Vascular invasion (81% had tumor inside vessel and attached to vessel wall), perineural invasion (19%) and soft tissue invasion usually reliable indicators of malignancy
  • May produce amyloid
  • Histologically, a definitive diagnosis of malignancy should be restricted to tumors displaying evidence of vascular invasion, capsular invasion with growth into adjacent tissues or metastases; criteria for vascular and capsular invasion are similar to those used in thyroid pathology: vascular invasion should be observed in the capsule or in the surrounding soft tissues
  • As criteria for malignancy are mostly architectural and require adequate sampling, frozen sections are of little value
  • Diffuse nuclear enlargement with macronucleoli suggests malignancy (J Cancer 2011;2:532)
  • May have pseudofollicular pattern (Mod Pathol 2000;13:210)
Microscopic (histologic) images

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Nests of neoplastic cells that are not very pleomorphic

Invasion of adjacent soft tissue and muscle

1: Infiltrates skeletal muscle
2: Mitotic activity
3: MIB1
4: PTH

Cytology images

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Guided aspirate showing highly cellular smear with stippled nuclear chromatin and moderate pleomorphism

Positive stains
Negative stains
Molecular / cytogenetics description

Pathogenesis:
  • Five genes with a potential role in malignancy have been identified and studied (J Bone Miner Res 2008;23:1869)
    1. p53
    2. Breast carcinoma susceptibility (BRCA2)
    3. Cyclin D1 / parathyroid adenomatosis gene 1 (PRAD1)
    4. Retinoblastoma tumor suppressor gene (RB)
    5. Hyperparathyroidism 2 tumor suppressor gene (HRPT2); has provided the best evidence