Accuracy, concordance, and reproducibility of histologic diagnosis in cutaneous T-cell lymphoma: an EORTC Cutaneous Lymphoma Project Group Study. European Organization for Research and Treatment of Cancer.
OBJECTIVE
To assess the level of observer variability in the histologic identification of cutaneous T-cell lymphoma (CTCL) and its discrimination from diseases with similar histologic features.


METHODS
Cutaneous T-cell lymphoma specimens and randomly mixed controls were evaluated twice by 3 examiners.


METHODS
The European Organization for Research and Treatment of Cancer (EORTC) Cutaneous Lymphoma Project Group.


METHODS
The study was conducted with histologic specimens from 32 patients with mycosis fungoides (MF). In addition, 13 specimens of spongiotic, lichenoid, or psoriasiform simulators of MF were blindly and randomly mixed with the CTCL specimens as controls.


METHODS
To evaluate the accuracy and concordance among and individual reproducibility of raters of histologic diagnoses.


RESULTS
Overall, the concordance among raters was fair to moderate (range, 0.283-0.562; weighted overall kappa, 0.412). Individual reproducibility of examiners ranged from moderate to almost perfect (range, 0.473-0.896; weighted overall kappa, 0.709) and was not significantly different for the definite lymphoma (range, 0.551-0.921; overall kappa, 0.802) and nonlymphoma (range, 0.368-0.950; overall kappa, 0.793) categories. Accuracy was similarly variable among raters: sensitivity ranged from 49.3% to 78.1% (overall kappa, 0.654), and specificity (control series) ranged from 46.2% to 69.2% (overall kappa, 0.595). Adding the diagnoses of probable lymphoma to those of definite lymphoma, sensitivity ranged between 73.5% and 84.9%. Although for each examiner there was a trend toward a lower sensitivity in the detection of early lesions compared with later lesions, the difference in sensitivity between the 2 groups was not statistically significant.


CONCLUSIONS
The levels of concordance and reproducibility found in this investigation were similar to those obtained with comparable studies in the most varied fields of pathology, confirming that the identification of CTCL for our observers did not cause particular problems. Our findings also revealed that pitfalls in CTCL identification are not only limited to early lymphomatous lesions, as commonly postulated.
Santucci
M
M
Dipartimento di Patologia Umana ed Oncologia, Università degli Studi di Firenze, Florence, Italy. Marco.Santucci@UNIFI.IT
Biggeri
A
A
Feller
A C
AC
Burg
G
G
D001706:Biopsy; D016009:Chi-Square Distribution; D006801:Humans; D016410:Lymphoma, T-Cell, Cutaneous / Q000473:pathology*; D009182:Mycosis Fungoides / Q000473:pathology; D015588:Observer Variation; D011897:Random Allocation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012867:Skin / Q000473:pathology; D012878:Skin Neoplasms / Q000473:pathology*