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Mitotic rate in primary melanoma: interobserver and intraobserver reliability, analyzed using H&E sections and immunohistochemistry
Author(s) -
Garbe Claus,
Eigentler Thomas K.,
Bauer Jürgen,
BlödornSchlicht Norbert,
Cerroni Lorenzo,
Fend Falko,
Hantschke Markus,
Kurschat Peter,
Kutzner Heinz,
Metze Dieter,
Mielke Volker,
Preßler Harald,
Reusch Michael,
Reusch Ursula,
Stadler Rudolf,
Tronnier Michael,
Yazdi Amir,
Metzler Gisela
Publication year - 2016
Publication title -
jddg: journal der deutschen dermatologischen gesellschaft
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.463
H-Index - 60
eISSN - 1610-0387
pISSN - 1610-0379
DOI - 10.1111/ddg.12797
Subject(s) - medicine , mitotic index , melanoma , kappa , reproducibility , immunohistochemistry , nuclear medicine , pathology , mitosis , biology , mathematics , cancer research , statistics , geometry , microbiology and biotechnology
Summary Background In 2009, the AJCC issued a revised melanoma staging system. In addition to tumor thickness and ulceration, the mitotic rate was introduced as the third major prognostic parameter for the classification of primary cutaneous melanoma. Given that, according to the 2009 AJCC classification, the detection of one or more dermal tumor mitoses leads to an upstaging – from stage Ia to Ib – of melanomas with a tumor thickness of ≤ 1.0 mm, we set out to investigate the reproducibility of this new parameter. Methods In order to assess interobserver reliability, 17 dermatopathologists und pathologists – all well versed in the diagnosis of cutaneous melanoma – analyzed the mitotic rate in 15 thin primary cutaneous melanomas (mean tumor thickness 0.91 mm) using identical slides. Mitotic rates were determined on H&E and phosphohistone H3 (Ser10)‐stained samples. Without knowledge of their previous assessment, five of the aforementioned examiners reevaluated the samples after more than one year in order to ascertain intraobserver reliability. Results Interobserver reliability of the mitotic rate in thin primary melanomas is disappointing and independent of whether H&E or immunohistochemically stained samples are used (kappa value: 0.088 [H&E], 0.154 [IH], respectively). Kappa values improved to 0.345 (H&E) and 0.403 (IH) when using a cutoff of 0/1 vs. 2+ mitoses. Similarly unsatisfactory, kappa values for intraobserver reliability ranged from 0.18 and 0.348, depending on the individual examiner. Discussion Given the unsatisfactory reproducibility and large variations in assessing the mitotic rate, it remains a matter of debate whether this diagnostic parameter should play a role in therapeutic decisions.