Clinicopathologic features of thyroid neoplasm with THADA-IGF2BP3 fusion

Abstract

Abstract Introduction/Objective Thyroid adenoma-associated (THADA)-IGF2BP3 fusions is related to strong overexpression of insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) mRNA and protein, increased IGF2 translation and IGF1 receptor signaling via PI3K and MAPK pathways. THADA-IGF2BP3 have been identified as an oncogenic event in thyroid neoplasms, but the clinicopathologic features have not been greatly evaluated. The purpose of this cases review is to describe the clinical and pathologic findings of thyroid nodules with THADA-IGF2BP3 fusion on molecular testing. Methods/Case Report Surgical Pathology 220 cases of total and hemithyroidectomy from January 2018 to December 2019 were reviewed for cytology fine needle aspiration (FNA), molecular testing results and surgical resection pathology. Results (if a Case Study enter NA) Three cases of THADA-IGF2BP3 fusion identified by Thyroseq testing from FNA of thyroid nodules with all diagnosed as atypia of undetermined significance, Bethesda category 3. No other mutations or gene fusions are identified. Successive surgical interventions are performed. Case 1 is a 49-year-old female right hemithyroidectomy with pathologic diagnosis of papillary thyroid carcinoma (PTC) follicular variant with tumor capsular invasion and no lymphvascular invasion. The tumor is 2cm, two lymph nodes evaluated are not involved by tumor and pathological stage is pT1b pN0. Case 2 is a 71-year-old female total thyroidectomy and the pathologic diagnosis is PTC follicular variant with tumor capsular invasion and no lymphvascular invasion. The tumor is 2cm, one lymph node evaluated is not involved by tumor and pathologic stage is pT1b pN0. Case 3 is a 76-year-old male left hemithyroidectomy and pathologic diagnosis is PTC follicular variant with tumor capsular invasion and no lymphvascular invasion. The tumor is 2cm, two lymph nodes evaluated are not involved by tumor and pathologic stage is pT1b pN0. Conclusion THADA-GF2BP3 fusion is uncommon in thyroid neoplasms and only three cases are detected in 220 cases evaluated. The three cases of thyroid nodules are all diagnosed as AUS by FNA, and all are diagnosed as PTC follicular variant with capsular invasion upon resection without lymphvascular invasion or lymph node involvement. THADA-F2BP3 fusion is associated with thyroid carcinoma, with low-risk non-aggressive behavior, conservative surgery appears necessary and lobectomy is likely adequate.