The Munich Nomenclature II, since 1990 officially in use for the German national cancer screening program, needed an update to account for the accumulated knowledge about the biology and epithelial cell transformation potential of HPV infection, to better represent glandular lesions in the cytological grading system, and to be translatable into the Bethesda System (TBS). Especially, ASC-US cytology had not been accounted for in the old grading system, thus reducing sensitivity of the cytological approach to detect potentially precancerous conditions of the cervix.
Members of the Coordination Conference for Cytology (delegates of the German professional and scientific societies for cytology, pathology and gynecology) drafted the updated Munich Nomenclature III (MN III), taking into consideration the continuity of the previous German grouping system and the traditional separation of mild (group IIID1), moderate (group IIID2) from severe dysplasia (IVa-p). In order to estimate the distribution of different diagnostic categories within MN III, statistical evaluation was performed for the results of five cytology labs across Germany based on 287,346 women over a six months period.
The referral labs did not encounter difficulties switching from MN II to MN III and altogether had a high NILM rate (Group I and II-a: 97.6 %), a low rate of ASC-US or ASC-H (II-p, 0.6% or III-p, 0.2%). LSIL (IIID1) rate was 0.7%, HSIL 0.6% (IIID2 and IVa-p/IVb-p: 0.4 and 0.2%). The rate of possible or precancerous glandular lesions (AGC (II-g or III-g) / AIS (IVa-g/IVb-g)) was low (0.1% / 0.004%). No significant differences were encountered for the rates of NILM and IVa-p+ rates of MN III compared to MN II, but with MN III it was possible to determine the ASC-US, LSIL and HSIL rates and the frequency of glandular lesions in German cytology labs . About one third of the cases with invasive cancer cytology (group V, 0.02%) were endometroid (V-e, 29%), only 12% glandular endocervical (V-g) and 51% of squamous differentiation.
MN II has successfully been replaced by MN III which is fully compatible with TBS. The frequency of ASC-US (group II-p) is lower than the LSIL, of ASC-H (III-p) considerably lower than HSIL rate, which indicates a good standard of quality in cytological screening diagnoses. The three tier system of squamous dysplastic lesions allows for a differentiated approach in follow-up (cytology for IIID1 and first time IIID2; colposcopy or excision biopsy for recurrent IIID2 or for IVa/b-p), and the determination of glandular or presumably glandular origin helps in the appropriate diagnostic work-up and proper therapeutic procedures for patients with these lesions.
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Griesser H, Marquardt K, Jordan B, et al.: Das Prozedere bei auffälligen Befunden.Kommentar zur Münchner Nomenklatur III. Frauenarzt 2015; 56: 10-33.
Marquardt K, Griesser H: Münchner Nomenklatur III: Befundverteilung in der Jahresstatistik. Frauenarzt 2015; 56: 108-110.