Analysis of tumor mitotic rate in thin metastatic melanomas compared with thin melanomas without metastasis using both the hematoxylin and eosin and anti-phosphohistone 3 IHC stain.

Studies have suggested that elevated tumor mitotic rate (MR) is linked to overall survival in thin melanoma. Recently, promising data regarding anti-phosphohistone 3 (pHH3) immunohistochemistry and its ability to aid in calculation of MR have emerged. The authors retrospectively analyzed original biopsies from 13 thin melanomas with positive sentinel node (SN) status and 16 thin melanomas with negative SN status. Both anti-pHH3 immunohistochemistry and the hematoxylin and eosin (H&E) stain were used to evaluate MR by 2 dermatopathologists blinded to SN status using the "hot spot" method. Intraclass coefficient values were attained to measure interobserver concordance and reliability of the pHH3 stain. By generating a receiver operating characteristic curve and analyzing the overall area under the curve, pHH3 was found to have good interobserver reliability. The relationship between MR and SN involvement was also evaluated, but this correlation was not statistically significant.