Endocrine Abstracts

Background

Following the 4th edition of WHO classification of thyroid tumors several pathologic entities were reclassified, mainly as a means of de-escalating addressed therapy. We herein present two rare types of thyroid cancer, hyalinizing trabecular tumor (HTT) and Warthin-like papillary carcinoma (WL-PTC).

Cases presentation

A 64-year-old female patient presented with an ultrasonographic 1.92 × 1.11 cm isoechoic thyroid nodule with intranodular vascularity. Fine–needle aspiration (FNA) cytology showed atypia of undetermined significance (TBS III). Three years later FNA was repeated due to nodule enlargement and the cytology was reported as suspicious of malignancy (TBS V). A total thyroidectomy was performed and the pathology report revealed HTT. Substitution levothyroxine therapy was started. Three months postoperatively the patient was in an excellent condition with undetectable thyroglobulin levels and negative antithyroglobulin antibodies. The second patient, a 54-year-old woman with a known history of Hashimotos’ disease, presented with an ultrasonographic 13 mm-thyroid nodule, with irregular margins and microcalcifications. The subsequent FNA cytology showed papillary thyroid carcinoma (PTC), probably a tall cell variant (TSB VI). The patient underwent a total thyroidectomy and the pathology revealed a WL-PTC. Ablation radioiodine treatment was offered and suppression levothyroxine treatment was started.

Discussion

Both variants have a female preponderance with a middle-aged occurence and are usually associated with lymphocytic thyroiditis. HTT incidence is not known, but it is considered to be a rare thyroid neoplasm with a characteristic trabecular growth pattern and hyalinization. In FNA thyroid samples HTT shares nuclear features of PTC, so that it is usually diagnosed only after thyroidectomy. Cell membrane and cytoplasmic positivity for Ki67 and somatic GLIS rearrangement, especially PAX8-GLIS3, are characteristic of HTT. The majority of these tumors is noninvasive and considered to be benign, nevertheless distant metastases have been reported. WL-PTC is a rare histological variant of papillary carcinoma with a similar prognosis to the classical PTC. Histopathologically it resembles the Warthin tumor of salivary glands. While at first it was considered a subtype of the oncocytic variant of PTC, it is now reclassified as a separate PTC variant.

Conclusion

Despite their rareness, both HTT and WL-PTC might be clinically encountered. They are generally considered to have a benign clinical behavior. More information regarding long-term courses is needed, in order to properly treat such patients and avoid unnecessary therapies