Feinnadelzytologie von Schilddrüsenknoten: Molekulare Diagnostik in der klinischen Routine

Zusammenfassung

Hintergrund und Fragestellung: Ergebnisse für den Nachweis von somatischen Punktmutationen und Rearrangements in Schilddrüsenknoten-Feinnadelaspirationszytologien (FNAZ) wurden bisher anhand von frischem Material gewonnen. Nach einer ersten retrospektiven Untersuchung untersuchten wir nun deren diagnostischen Nachweis prospektiv an routinemäßig erstellten, konsekutiven, luftgetrockneten Proben.

Methodik: 154 konsekutive luftgetrocknete Routine-FNAZ-Ausstrichen wurden untersucht: 80 mit mikrofollikulärer Neoplasie (MFP), 45 mit follikulärer Neoplasie (FN), 26 mit Verdacht auf papilläres Schilddrüsenkarzinom (V. a. PTC) und 3 mit Verdacht auf Malignität. PAX8/PPARG- und RET/PTC3-Rearrangements wurden mittels quantitativer PCR nachgewiesen, während BRAF- sowie RAS-Punktmutationen durch Pyrosequenzierung identifiziert wurden.

Ergebnisse: Nur in 0,7 % und 5,3 % der FNAZ-Ausstriche war keine Analyse der Punktmutationen beziehungsweise der Rearrangements möglich. NRAS-Mutationen konnten in 7 Proben mit MFP, und je einmal bei FN bzw. V. a. PTC nachgewiesen werden; HRAS-Mutationen wurden je einmal in Proben mit MFP und FN identifiziert. Eine KRAS-Mutation wurde lediglich in einer Probe mit FN nachgewiesen. Dagegen fanden sich BRAF-Mutationen in 20 FNAZ-Ausstrichen mit V. a. PTC, aber in keinem anderen Fall. PAX8/PPARG wurde in 2 Proben mit MFP nachgewiesen (in keinem anderen Fall), während RET/PTC3 nur einmal, und zwar bei MFP identifiziert wurde. Insgesamt enthielten 13,8 % der MFP-FNAZ, 6,7 % der FN-FNAZ und 80,8 % der V. a. PTC-FNAZ eine Mutation.

Folgerung: Der Nachweis von Rearrangements und Punktmutationen in Schilddrüsenknoten-Feinnadelaspirationszytologien ist in einem diagnostischen Routine-Setting möglich und kann zu klinischen Konsequenzen führen.

Abstract

Background and objective: Results for the detection of point mutations and rearrangements have thus far been obtained by fresh material of fine needle aspiration cytology (FNAC). After a first retrospective study we report on the diagnostic detection in routinely obtained, consecutive air-dried FNAC smears.

Methods: RNA and DNA was extracted from 154 consecutive routine air-dried FNAC smears: 80 with microfollicular proliferation (MFP), 45 with follicular neoplasia (FN), 26 with the cytological diagnosis of papillary carcinomas (PTC) and 3 which were suspicious for malignancy. PAX8/PPARG and RET/PTC3 rearrangements were detected by qPCR, while BRAF and RAS point mutations were detected by pyrosequencing.

Results: Only 0.7 % and 5.3 % of the routine air-dried FNAC samples did not allow analysis of a point mutation or rearrangements, respectively. NRAS mutations could be detected in 7 MFP smears, and in one of FN and PTC samples, respectively. HRAS mutations were detected in one MPF and one FN sample. A KRAS mutation was only detected in one FN sample, whereas BRAF mutations were detected in 20 samples with PTC (but in no other sample). PAX8/PPARG was detected in 2 MFP samples, while RET/PTC was detected in only one MFP sample. In total, 13.8 % MFP-FNAC, 6.7 % FN-FNAC, and 80.8 % PTC-FNAC samples harbored a mutation.

Conclusion: These results demonstrate that rearrangements and point mutations can be detected in routinely obtained air-dried FNAC samples.

Schlüsselwörter

Schilddrüsenknoten - Feinnadelaspirationszytologie - Molekularpathologie - BRAF-Mutation - Rearrangements

Keywords

thyroid nodules - fine-needle asipration cytology - molecular analysis - BRAF mutation - rearrangements

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