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Papillary carcinoma of the thyroid

Papillary carcinoma accounts for 80% of thyroid malignancies3. It is the most prevalent endocrine carcinoma.

Immunohistochemistry

Molecular genetics

There are three mutations commonly present in papillary carcinomas of the thyroid and each associated with specific features8:

• BRAF mutations were associated with:

  •  older patient age
    
  • typical papillary appearance or the tall cell variant
    
  • a higher rate of extrathyroidal extension, and more advanced tumor stage at presentation.

• RET/PTC mutations:

  •  presented at younger age
    
  • have a predominantly typical papillary histology with frequent psammoma bodies
    
  • a high rate of lymph node metastases.
• RAS mutations:
  • are exclusively found in the follicular variant of papillary carcinoma
    
  • correlated with a low rate of lymph node metastases.

Differential diagnosis

• The follicular variant of papillary carcinoma: follicular adenoma and follicular carcinoma of the thyroid.

• There is a solid variant of papillary carcinoma with a differential diagnosis which includes poorly differentiated carcinoma, medullary carcinoma, anaplastic carcinoma and metastatic carcinoma to the thyroid. It has a slightly worse prognosis than the classical papillary type but much better than poorly differentiated carcinoma. It has the same nuclear morphology and immunohistochemical profile as the classical papillary type.3

Management

Treatment is by thyroidectomy, radioiodine ablation of the thyroid remnants and TSH-suppressing doses of thyroxine.

Prognosis

With treatment, mortality is less than 10%.

References

1 Diagnostic histopathology of tumors. Edited by CDM Fletcher. 2nd edition. Churchill Livingstone. Pages 975-6.

2 Keen, C. E., Szakacs, S., Okon, E., Rubin, J. S., Bryant, B. M. CA125 and thyroglobulin staining in papillary carcinomas of thyroid and ovarian origin is not completely specific for site of origin Histopathology 1999;34:113-117

3 Nikiforov, Y. E., Erickson, L. A., Nikiforova, M. N., Caudill, C. M., Lloyd, R. V. Solid variant of papillary thyroid carcinoma: incidence, clinical- pathologic characteristics, molecular analysis, and biologic behavior. Am J Surg Pathol 2001;25:1478-1484.

4 Bejarano, P.A., Nikiforov, Y.E., Swenson, E.S. and Biddinger, P.W. Thyroid transcription factor-1, thyroglobulin, cytokeratin 7, and cytokeratin 20 in thyroid neoplasms. Appl Immunohistochem Mol Morphol 2000;8:189-94.

5 Cvejic, D., Savin, S., Paunovic, I., Tatic, S., Havelka, M. and Sinadinovic, J. Immunohistochemical localization of galectin-3 in malignant and benign human thyroid tissue. Anticancer Res 1998;18:2637-41.

6 Beesley, M.F. and McLaren, K.M. Cytokeratin 19 and galectin-3 immunohistochemistry in the differential diagnosis of solitary thyroid nodules. Histopathology 2002;41:236-43.

7 Fernandez, P.L., Merino, M.J., Gomez, M., Campo, E., Medina, T., Castronovo, V., Sanjuan, X., Cardesa, A., Liu, F.T. and Sobel, M.E. Galectin-3 and laminin expression in neoplastic and non-neoplastic thyroid tissue. J Pathol 1997;181:80-6.

8 Adeniran AJ, Zhu Z, Gandhi M, et al. Correlation between genetic alterations and microscopic features, clinical manifestations, and prognostic characteristics of thyroid papillary carcinomas. Am J Surg Pathol 2006; 30:216-22

9 Zafon C, Obiols G, Castellvi J, et al. Clinical significance of RET/PTC and p53 protein expression in sporadic papillary thyroid carcinoma. Histopathology 2007; 50:225-31

10 Tretiakova MS, Sahoo S, Takahashi M, et al. Expression of alpha-methylacyl-CoA racemase in papillary renal cell carcinoma. Am J Surg Pathol 2004; 28:69-76

This page last revised 30.1.2007.