Detection of mitotic figures in thin melanomas--immunohistochemistry does not replace the careful search for mitotic figures in hematoxylin-eosin stain.
BACKGROUND
The mitotic rate is an important prognostic criterion in patients with thin melanoma ≤ 1 mm.


OBJECTIVE
The aim of this study was to investigate the reproducibility of the mitotic rate in thin melanoma in hematoxylin-eosin (H&E) stain and compare it with the detection of mitotic figures by immunohistochemistry.


METHODS
The number of mitoses stated in the routine diagnostic report in 190 pT1 melanomas was compared with the number gained from re-evaluation of H&E sections and the number detected after staining with the mitotic marker, phosphohistone H3 (PHH3). Two different approaches were used for choosing the "hot spot" for evaluation (dermal vs epidermal/dermal).


RESULTS
Comparing routine H&E-stained slides with re-evaluation slides, the number of mitotic figures was slightly variable. However, findings did not result in a change of the tumor stage. In 34% of the tumors with dermal mitotic figures on H&E, mitoses could not be found in the corresponding PHH3 slide anymore. In 4% of the cases, stage relevant mitoses could only be found by PHH3 immunohistochemistry.


CONCLUSIONS
This is a single center study.


CONCLUSIONS
Immunohistochemical staining for mitotic figures does not replace a careful evaluation of H&E-stained slides. Immunohistochemical detection of mitosis is only an additional tool; the time-saving effect is therefore negligible.
Department of Dermatology, Venereology, and Allergology, HELIOS-Klinikum Hildesheim, Hildesheim, Germany.
Karl
K
Ottmann
Department of Dermatology, Venereology, and Allergology, HELIOS-Klinikum Hildesheim, Hildesheim, Germany.
Michael
M
Tronnier
Department of Dermatology, Venereology, and Allergology, HELIOS-Klinikum Hildesheim, Hildesheim, Germany. Electronic address: christina.mitteldorf@helios-kliniken.de.
Christina
C
Mitteldorf
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D015331:Cohort Studies; D016208:Databases, Factual; D018450:Disease Progression; D004801:Eosine Yellowish-(YS); D005260:Female; D006416:Hematoxylin; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D008938:Mitosis / Q000502:physiology*; D008940:Mitotic Index; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013194:Staining and Labeling / Q000379:methods*; D018709:Statistics, Nonparametric; D055815:Young Adult
D004801:Eosine Yellowish-(YS); D006416:Hematoxylin
hot spot; immunohistochemistry; mitosis; mitotic rate; pT1; phosphohistone H3; thin melanoma