ESPE Abstracts

Background: Hyalinizing trabecular tumour is a rare, begin thyroid neoplasm, which shares some histologic features with thyroid papillary carcinoma or medullary carcinoma. Sometimes it is misdiagnosed as papillary carcinoma on fine-needle aspiration cytology (FNAC). The aetiology of hyalinizing trabecular tumour is unknown. The tumour may arise in a background of chronic lymphocytic thyroiditis, multinodular goitre, or after radiation exposure. Hyalinizing trabecular adenoma (HTA) is predominantly diagnosed in middle-aged women. In children it is casuistic

Case presentation: We present the case of 17-year-old boy, who was diagnosed in our Outpatient Clinic of Endocrinology due to an asymptomatic left neck mass suggestive of a thyroid tumour. Clinical examination confirmed the diagnosis of the nodule within the left lobe of thyroid gland, without lymph nodes metastases. Serum thyroid hormones and thyroid antibodies were in normal range. An ultrasound of the neck confirmed the presence of solid nodule measuring 38.7×24.5×28.7 mm and mixed blood flow (with predominance of peripheral flow) within nodular change. In elastography this nodule was tough (typical for malignancy) with elasticity index ROI1/ROI2=5. A papillary thyroid carcinoma (PTC) was diagnosed by FNAC. Total thyroidectomy was performed, with hypothyroidism as a post-surgical result. Immunohistochemistry was positive for thyroglobulin but negative for calcitonin, eliminating the possibility of medullary carcinoma. The cells of tumour had a Ki-67 reactivity at the cell membrane and cytoplasm, characteristic of hyalinizing trabecular tumour. There was no area of focal capsular invasion. A final pathological diagnosis of hyalinizing trabecular adenoma was reported. The patient’s treatment with an ablative dose of radioactive iodine was redundant. Now he is euthyroid with thyroid replacement and has no evidence of recurrence at 6 months of follow-up.

Conclusion: In conclusion, distinction of hyalinizing trabecular adenoma from thyroid papillary carcinoma in cytologic specimen is very difficult. Diagnosis of a thyroid tumour determinate appropriate management.