Abstract
Extra-osseous Ewing sarcoma (ES) is a rare and aggressive malignant tumor found in a variety of organs. Primary ES of the thyroid is exceedingly rare and few cases have been documented to date. We describe the case of a 54-year old woman with a history of breast carcinoma in whom a unique hypermetabolic left thyroid nodule was identified during a follow-up PET-CT scan. An ultrasound examination showed a hypoechogenic nodule of 3.7 cm. A cytological diagnosis of poorly differentiated thyroid carcinoma was made, and a total thyroidectomy was performed. The surgical specimen revealed a poorly differentiated neoplasm composed of medium-sized cells with scant cytoplasm, expressing pancytokeratin, CD99 and NKX2.2 but lacking p63 and p40 expression. Molecular analysis revealed a EWSR1-FLI1 fusion transcript supporting the diagnosis of a primary extra-osseous ES of the thyroid. The patient received adjuvant chemotherapy and has no evidence of recurrent disease.
Highlights
Thyroid cancers encompass a wide range of tumors, from indolent cases with low mortality to extremely aggressive malignancies with short overall survival
Mesenchymal thyroid neoplasms are exceedingly rare among which Ewing sarcoma (ES) represents only 2% [2]
An US-guided fine needle aspiration (FNA) was performed which showed a monomorphic proliferation of dyscohesive cells isolated and in groups, with scant cytoplasm and distinct small nucleoli (Fig. 1A)
Summary
Thyroid cancers encompass a wide range of tumors, from indolent cases with low mortality to extremely aggressive malignancies with short overall survival. A 54-year old woman presented with a 3.7 cm nodule in the left thyroid lobe during a routine PET-scan follow-up for a triple negative breast carcinoma, without BRCA-1 or BRCA-2 mutation, treated with neoadjuvant chemotherapy, surgery, and radiotherapy. An US-guided fine needle aspiration (FNA) was performed which showed a monomorphic proliferation of dyscohesive cells isolated and in groups, with scant cytoplasm and distinct small nucleoli (Fig. 1A). Based on the cytomorphology and immunocytochemical profile a diagnosis of poorly differentiated thyroid carcinoma (PDTC) was made, and the patient underwent a total thyroidectomy. The surgical specimen of the left thyroid lobe showed a poorly delineated cream-colored nodule with hemorrhagic zones, measuring 4 cm, occupying the superior and medial part of the thyroid, which was extensively sampled. The cells were negative for PAX-8, thyroglobulin, CEA, calcitonin, p63, p40 (Fig. 2C), chromogranin, synaptophysin, hormonal receptors (ER, PR), GATA3, mammaglobin and BRST2. The patient is in remission with no local recurrence no distant metastases
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