The evolution of differentiated thyroid cancer

Differentiated thyroid tumours of follicular cell derivation have traditionally been classified based on architecture, cytology, or both. The features that distinguish the various entities are controversial and diagnostic criteria are inconsistent and often irreproducible. The complexity of classification schemes has not been substantiated by molecular profiling. In this review, a simplistic approach to the diagnosis of well differentiated thyroid neoplasia is provided to challenge the dogma. The proposed classification matches the molecular profiles of these lesions and simplifies the criteria for diagnosis. This approach can be used to support rational treatment algorithms.

Galectin-3 Immunohistochemical Expression in Thyroid Neoplasms

BACKGROUND

Galectin-3 has been implicated in the regulation of cellular growth, differentiation and malignant transformation in various organs including thyroid gland. It has been extensively studied as an immunohistochemical (IHC) marker in thyroid malignancy.

AIM

To evaluate the diagnostic role of Galectin-3 (Gal-3) in differentiating malignant from benign thyroid neoplasm.

MATERIALS AND METHODS

In this observational study we evaluated Gal-3 expression in a spectrum of malignant (30) and benign (20) thyroid neoplasms. The final common diagnosis arrived at after histopathologic evaluation of H&E stained sections by two pathologist's was considered the gold standard. The malignant neoplasms included Papillary Thyroid Carcinoma (PTC), Follicular Thyroid Carcinoma (FTC), Medullary Thyroid Carcinoma (MTC), insular carcinoma, Anaplastic Thyroid Carcinoma (ATC), and metastatic carcinoma. The benign neoplasms included Follicular Adenoma (FA), Hurthle cell adenoma and hyalinizing trabecular adenoma. IHC staining for Gal-3 was performed for all neoplasms with the polymeric method using lyophilized mouse monoclonal antibody.

STATISTICAL ANALYSIS

Statistical analysis was done using 2x2 contingency table. Chi-square test with Yates correction was used to calculate p-value to ascertain statistical significance.

RESULTS

Gal-3 expression was significantly higher in malignant thyroid neoplasms as compared to benign neoplasms (p<0.0001). Gal-3 expression in differentiating malignant from benign neoplasms was found to have sensitivity of 86%, specificity of 85%, positive predictive value of 89.66% and negative predictive value of 80.95%. However, no statistical significance was observed (p=0.4718) when comparing PTC and other malignant lesions in terms of Gal-3 expression. Gal- 3 expression in PTC was found to have sensitivity of 91.3%, specificity of 85%, positive predictive value of 87.5% and negative predictive value of 89.47%.

CONCLUSION

Diffuse and strong IHC staining for Gal-3 differentiates malignant from benign tumours. This marker can assist in the diagnosis of thyroid neoplasms with equivocal morphologic features. This study highlights the high sensitivity of Gal-3 for PTC.

Primary paraganglioma of thyroid gland: a clinicopathologic and immunohistochemical study with review of the literature

Primary paraganglioma of the thyroid is a very rare neuroendocrine tumour. Only 24 cases have been reported in the Literature. A case of a primary paraganglioma of the thyroid is presented in order to provide a review of the Literature, an update on current knowledge and to emphasize the key diagnostic role of immunohistochemistry. A 63-year-old female presented with a 6-month history of right-sided solitary thyroid nodule. Ultrasonography and fine needle aspiration biopsy were not diagnostic. The patient underwent right hemithyroidectomy. The tumour cells showed a strongly positive staining for chromogranin A, synaptophysin and neuron specific enolase, whereas S-100 protein was positive in sustentacular cells. A diagnosis of primary paraganglioma of the thyroid was made. Radiotherapy for suspected local tumour persistence was planned. At 18-months follow-up, the patient is alive without evidence of recurrence. This case highlights the need to include primary paraganglioma of the thyroid in the differential diagnosis of neuroendocrine intra-thyroidal tumours. Immunohistochemistry is essential for diagnosis. Surgery is the treatment of choice.