Endocrine Abstracts

Introduction: Primary malignant thyroid teratoma is a rare neoplasm. Even rarer is the concomitance of the mentioned tumor and papillary thyroid cancer.

Case report: We report a case of a 44-year old woman diagnosed with Hasimoto thyroiditis and multinodular, non-toxic goiter since 2004. The two larger, initially non palpable nodules were located in right thyroid lobe, 16 and 12 mm in diameter respectively. Under suppressive thyroxine therapy the diameter of the two nodules constantly increased (2005–20 and 12 mm, 2006–23 and 12.6 mm, 2007–25 and 15 mm, 2008–30 and 22 mm). The nodules were palpable in physical examination since 2007. Two FNA biopsies of the described nodules on 1/2005 and 12/2006 revealed benign/reactive cytopathology, without any indication of malignancy. Due to continuous nodule enlargement, thyroidectomy was suggested and performed on 12/2008. Histopathological evaluation of the resected thyroid gland (subtotal thyroidectomy) revealed chronic thyroiditis and i) lesion of malignant teratoma (~2.5 cm) with primitive mesenchymal, neuroectodermal and epithelial tissue from grade 1 to grade 3 and ii) lesion (~1 cm) of papillary thyroid carcinoma (collision tumors) of follicular variant cells, evading thyroid capsule. After thorough whole body radiological evaluation, no site of possible primary neoplasm was recognized and the diagnosis of primary malignant thyroid teratoma was set. Three sessions of adjuvant chemotherapy, based on cis-platinum, followed the surgical resection for the stage 1 teratoma and RAI therapy with 70 mCi ¹³¹I for the stage 1 papillary thyroid cancer. Further periodic laboratory and radiologic evaluation support disease remission. Two years after subtotal thyroidectomy and 1.5 years after adjuvant therapy completion, there is no sign of regional or distal tumor relapse.

Conclusion: Concomitant primary malignant thyroid teratoma with papillary thyroid cancer is an extremely rare, if not the unique, case. Early diagnosis is critical for successful therapy. Complex cancer cases like this demand multidisciplinary approach, in order to achieve maximal patient survival.