Automated quantification of MART1-verified Ki-67 indices: useful diagnostic aid in melanocytic lesions

Automated quantification of Ki67/MART1 stains may prevent false‐negative melanoma diagnoses

“…Lesions were classified as malignant if the Ki67 index was above the designated cut‐off point; otherwise they were classified as benign. Cut‐off points of all indices were established in our previous study by two‐way receiver operating characteristic (ROC) curves, although cut‐off points of number‐based indices were left unpublished . We previously established that a cell count of minimally 250 melanocytic cells, equal to a MART1‐verified tumor area of approximately 0.13 mm 2 , is reasonable for a valid result .…”

“…Using our previously presented automated algorithm based on the area of melanocytic cells in dermis and its associated cut‐off point, we were able to correctly classify all melanomas (Table ). Nevertheless, the index of three lesions (patient ID, 2, 9 and 10) were very close to the chosen cut‐off point (0.14), and they were occasionally misclassified by either the hot‐spot index or the number‐based index (Table ); hence, they were borderline cases that possibly are difficult to diagnose solely by proliferation.…”

“…BenchMark XT (Ventana Medical Systems, Tucson, AZ, USA) conducted Ki67/MART1 and PHH3/MART1 stains by an indirect sequential immunoenzymatic technique on 4‐µm sections mounted on Superfrost Plus slides (Thermo Fisher Scientific, Waltham, MA, USA) . Monoclonal rabbit antibody Ki67 (Clone SP6; 1:100; 32 min; Thermo Fisher Scientific), polyclonal rabbit antibody Phospho‐Histone H3 (Ser10; 1:300; 32 min; Cell Signaling Technology, Inc., Danvers, MA, USA), and monoclonal mouse antibody MART‐1 (M2‐7C710, 1:50; 40 min; Cell Marque Corporation, Rocklin, CA, USA) were utilized and visualized by Ventanas ultraView Universal Detection Kits: 3,3′‐Diaminobenzidin (DAB) and alkaline phosphatase red.…”

“…Two fixed VIS image analysis protocols, previously established and described, were utilized, that is, one protocol established the area of epidermis (Fig. G), and the other, the area and number of melanocytic cells (Fig.…”

“…Recently, its high diagnostic performance was validated in a large prospective and consecutive cohort with melanocytic lesions ( N = 376). With very high certainty, automated indices based on the area of proliferative melanocytic cells in both dermis and epidermis, and especially a combination of such, were able to differentiate benign and malignant lesions . To prevent false‐negative melanomas, inclusion of such an algorithm thus seems valuable in melanoma diagnosis.…”