456 chapter 11 Results Study cohort baseline Forty-six patients with CNA-LOH analysis using the GWLOH v2 panel on 48 nodules were screened for eligibility. Fourteen (29%) nodules, all with an ultrasound size smaller than 40 mm, were excluded because no surgery was performed, mainly due to the patients’ age and comorbidities. Four (9%) nodules with CNA-LOH analysis on (oncocytic cell) cytology were excluded because subsequent histopathology revealed a non-oncocytic cell lesion. Finally, 29 patients with 30 nodules were included (Table 1), including three (10%) with a histopathological diagnosis of NH-H, 11 (37%) OA, and 16 (53%) OCA including 13 (43%) minimally invasive (mi-OCA) and three (10%) widely invasive OCA (wi-OCA). There were no nondiagnostic CNA-LOH results. CNA-LOH analysis On CNA-LOH analysis using the GWLOH panel, CNA were observed in 25 of 30 (83%) lesions, including 10 of 11 (91%) OA, 12 of 13 (92%) mi-OCA, and 3 of 3 (100%) wi-OCA (Table 2, Figure 6). The CNA patterns were different between the histopathological subgroups (p<0.001). GH type CNA was found in 18 nodules, including 4 of 11 (36%) OA, 11 of 13 (85%) mi-OCA, and all wi-OCA. GH type CNA most frequently included chromosomes 2, 9, and 22, followed by 1, 3, 4, 6, 8, and 14. Chromosomes 7 and 12 were never involved. More chromosomes were affected in OCA (median 12 [IQR 7-16]) than OA (4 [3-9], p=0.04), but not in mi-OCA (12 [5-15]) as compared to wi-OCA (17 [8-17], p=0.06). Possible endoreduplication was observed in eight lesions, including one patient with American Joint Committee on Cancer stage I, four with stage III, and three with stage IVc disease (p=0.009) [17]. The median number of affected chromosomes in lesions with suspected endoreduplication was higher (15 [IQR 12-17]) than in lesions without (4 [4-9], p<0.001). (Possible) heterogenicity was observed in 4 of 4 (100%) OA and 5 of 14 (36%) OCA with GH type CNA (p=0.08). RCI type CNA were observed in seven nodules, including 6 of 11 (55%) OA and one equivocal case of mi-OCA (Table 2, case 16, further discussed below). CNA were detected as the only genetic alteration in 12 of 16 (75%) OCAs. Three mi-OCA and one wi-OCA showed an additional molecular driver, including one EIF1AX, two TERT promoter, and one TP53 mutation. Morphological and molecular diagnoses were discordant case 14, 15, 16 (illustrated below), 17, 18, and 23 (illustrated below) (Table 2, Figure 6).
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