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3p25 Aneusomy in Follicular Thyroid Neoplasms: A Report of Three Cases with Review of Literature

Case report

Abstrak

Aneusomi merupakan perubahan genetik awal dan suatu ciri utama dalam kebanyakan tumor pejal. Penemuan aneusomi biasanya dikaitkan dengan pesakit kanser dengan prognosis buruk. Penglibatan penyusunan semula gen PAX8-PPARγ dalam tumorigenesis lesi tiroid folikular telah dikaji. Namun begitu, tidak banyak laporan yang melaporkan kehadiran aneusomi gen PPARγ pada lokus 3p25 pada lesi tiroid folikular. Samada kehadiran keabnormalan ini dapat meningkatkan diagnosis, pengkelasan atau prognosis masih tidak dapat ditentukan. Kajian ini melaporkan penemuan aneusomi dalam tiga lesi tiroid folikular [dua karsinoma tiroid folikular (FTC) dan satu kes adenoma sel Hurthle (HCA)] yang menunjukkan kehadiran aneusomi 3p25 menerusi teknik penghibridan in-situ berpendaflur (FISH). Trisomi 3p25 telah ditemui pada satu kes FTC dan satu kes HCA manakala satu kes FTC menunjukkan tetrasomi 3p25. Lesi sel Hurthle berbeza dari segi klinikal dan histologikal daripada neoplasma folikular yang lain. Namun, penemuan aneusomi dalam HCA dan FTC menunjukkan kewujudan pertalian biologi di antara neoplasma sel Hurthle dan folikular. Di samping berkongsi ciri-ciri histologi dengan neoplasma tiroid konvensional, neoplasma sel Hurthle mungkin berkongsi perubahan genetik yang sama di peringkat awal pembentukan tumor folikular.

Abstract

Aneusomy is an early genetic event and a characteristic feature of many solid tumors. It is often associated with poor prognosis in cancer patients. The involvement of PAX8-PPARγ rearrangement in tumorigenesis of follicular thyroid lesions has been widely assessed. However, there were few reports on aneusomy of the PPARγ gene at the 3p25 locus in follicular thyroid lesions. It remains undetermined whether these abnormalities can be translated into improved diagnosis, classification, or outcome prediction. Herein, we report three cases of follicular thyroid neoplasms [two follicular thyroid carcinomas (FTCs) and one Hurthle cell adenoma (HCA)] with 3p25 aneusomy detected by fluorescence in situ hybridization (FISH). 3p25 trisomy was observed in one FTC and one HCA while 3p25 tetrasomy was observed in one FTC. Furthermore, all three lesions did not show overexpression of PPARγ protein. Hurthle cell neoplasms (HCN) are distinct clinically and histologically from other follicular thyroid neoplasms (FTN). However, the presence of the aneusomy in HCA and FTC indicates that there could be a biological continuum between the two and chromosomal gains might play an important role in the pathogenesis of these two types of neoplasms. Despite their differences, HCN and FTN may share the same early genetic event in tumour development.