Interobserver reproducibility of histopathologic prognostic variables in primary cutaneous melanomas.
BACKGROUND
The prognosis for patients with localized primary cutaneous melanoma is known to depend principally on tumor thickness, and to a lesser extent on ulcerative state and Clark level. We have recently found in an analysis of 3661 patients that tumor mitotic rate (TMR) is also an important prognostic parameter, ranking second only to tumor thickness. However, few studies have assessed the accuracy and reproducibility with which these features of a melanoma are recorded by histopathologists.


OBJECTIVE
To assess interobserver reproducibility of major pathologic prognostic parameters in cutaneous melanoma.


METHODS
Single hematoxylin and eosin-stained slides of 69 dermally invasive primary cutaneous melanomas were circulated among six pathologists with differing experience in the assessment of melanocytic tumors. The observers independently determined the tumor thickness, Clark level of invasion, ulcerative state, and TMR for each lesion. Intraclass correlation coefficients and kappa scores for multiple ratings per subject were calculated.


RESULTS
The intraclass correlation coefficients were 0.96 for tumor thickness and 0.76 for TMR. The kappa scores were 0.83 for ulcerative state and 0.60 for Clark level. These results indicated excellent agreement among the pathologists for measurements of tumor thickness, ulcerative state, and TMR and fair to good agreement for Clark level.


CONCLUSIONS
Appropriately trained and experienced histopathologists can assess prognostically important features of melanomas accurately and reproducibly. Given our recent finding of the significance of TMR in determining prognosis, it is important that this feature be assessed by a standardized method and documented for all primary cutaneous melanomas.
Scolyer
Richard A
RA
Department of Anatomical Pathology, and Sydney Melanoma Unit, and the Melanoma and Skin Cancer Research Institute, Royal Prince Alfred Hospital, Sydney, NSW, Australia. richard.scolyer@email.cs.nsw.gov.au
Shaw
Helen M
HM
Thompson
John F
JF
Li
Ling-Xi L
LX
Colman
Marjorie H
MH
Lo
Sing Kai
SK
McCarthy
Stanley W
SW
Palmer
A Allan
AA
Nicoll
Katherine D
KD
Dutta
Bish
B
Slobedman
Eric
E
Watson
Geoff F
GF
Stretch
Jonathan R
JR
D006801:Humans; D008545:Melanoma / Q000453:epidemiology* / Q000473:pathology*; D015588:Observer Variation; D011379:Prognosis; D015203:Reproducibility of Results; D012878:Skin Neoplasms / Q000453:epidemiology* / Q000473:pathology*