NIS Amplification In A Rare Combination of Three Histological Subtypes of Collision Tumours of Thyroid Gland Identified by Whole Body I 131 and PETCT Imaging Volume 7 - Issue 4

P Shanmuga Sundaram* and Subramanyam Padma

• Clinical Professors, Department of Nuclear Medicine & Molecular Imaging, Amrita Institute of Medical Sciences & Research Centre, Amrita Vishwa vidyapeetham University, Kerala, India

Received: November 15, 2021;   Published: November 30, 2021

Corresponding author: P Shanmuga Sundaram, Clinical Professor, Department of Nuclear Medicine & Molecular Imaging, Amrita Institute of Medical Sciences & Research Centre, India

DOI: 10.32474/SJO.2021.07.000269

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Abstract

Radio iodine (I 131) is popularly called as a ‘magic bullet’ due to its maximum tumoricidal action (with least side effects) over thyroid remnant as well as in metastatic deposits in postoperative settings of Differentiated thyroid cancers (DTC). However, for undifferentiated and rare squamous cell thyroid cancers, different treatment options have been described which include surgery, chemotherapy and radiation with poor outcomes. Orally administered I 131 is maximally beneficially in thyrocytes concentrating I 131. Its targeted tumoricidal action is based on the crossfire effect arising from the 606 kilo electron volts beta irradiation that it exerts on thyrocytes. We present a case of an elderly lady with a rapidly enlarging neck mass. Patient underwent total thyroidectomy, cervical nodal clearance, and extensive tumour debulking followed by external radiotherapy to neck. Histopathology revealed collision tumour consisting of 3 different thyroid cancers; one component of differentiated (papillary) and 2 undifferentiated (Squamous cell Ca, SCC and anaplastic) variants. 18F Flurodeoxyglucose Positron emission tomography – computed tomography, FDG PETCT imaging was performed as part of the staging workup for SCC. PETCT showed a large neck mass with local infiltration and nodal metastases. Although stimulated thyroglobulin (Tg) was only 0.04 ng/ml, based on the DTC component, I 131 whole body scan was performed. Images revealed I 131 uptake due to sodium iodide symporter (NIS) expression in DTC part of the residual neck mass that was FDG negative (‘Flip flop phenomenon – I 131 positive but FDG negative’). Due to the identification of I 131 concentrating papillary component, patient was considered suitable for high dose I 131 therapy. Nuclear medicine investigation has helped in the staging of thyroid malignancy, prognosticating the aggressive nature of disease and by way of demonstrating NIS amplification in part of neck mass, received therapeutic benefit in the form of high dose I 131 therapy.

Keywords: Radio iodine, Collision tumour; thyroid gland; Undifferentiated thyroid cancer; Anaplastic thyroid cancer; Squamous cell thyroid cancer

Abstract| Introduction| Case Presentation| Discussion| Conclusion| Acknowledgement| Conflict of Interest| References|