Through careful clinicopathologic correlation, we identified 37 metastatic melanomas in the skin, all of which had intraepidermal components. These were compared with 43 microscopically similar primary melanomas with a predetermined panel of immunostains in general use in surgical pathology, including bcl-2 protein, mutant p53 protein, Ki-67 (MIB-1), proliferating cell nuclear antigen (PCNA), alpha-isoform actin, and CD117 (c-kit protein). There was no significant difference in bcl-2 or alpha-isoform actin staining patterns of primary vs secondary cutaneous melanomas. The expression of Ki-67 generally was higher in metastatic melanomas than in primary lesions, and the same was true of mutant p53 protein labeling; however, some overlap was observed. CD117 staining was retained in 65% of metastatic melanomas (24/37) when they originated from ocular primary tumors; nevertheless, that marker was lost in virtually all of the other metastatic melanocytic neoplasms, whereas primary melanomas demonstrated consistent reactivity for c-kit protein. Although they are not definitive, these trends in immunoreactivity could facilitate the process of distinguishing the multiple primary melanoma syndrome from melanomatous metastases to the skin. That undertaking is best approached with circumspection, because clinicopathologic discriminators for this diagnostic separation are still imperfect.

Journal of Cutaneous PathologyDiagnostic concordance rates in the subtyping of basal cell carcinoma by different dermatopathologists Background There are numerous subtypes of basal cell carcinoma (BCC). Defining the histopathologic subtype is an essential element in patient management, but there is little known data regarding interobserver precision in subtyping BCC. Methods We studied interobserver variance between six board-certified dermatopathologists who subtyped 100 BCCs in a blinded fashion. We used kappa statistic to calculate the concordance in suggested subtype by different dermatopathologists. Provided diagnoses were then re-categorized into low-risk and high-risk phenotypes, and kappa statistic for concordance on high-risk BCC was determined. Results The overall κ statistic was 0.301, indicating fair agreement among the six observers. Superficial and fibroepithelial BCC had the highest individual kappa statistics. When subtypes were re-classified into a two-tier system of high-risk and low-risk phenotypes, there was substantial interobserver agreement on high-risk BCC with a κ statistic of 0.699. Conclusion These results suggest only fair agreement among dermatopathologists on specific BCC subtypes, but substantial agreement on superficial, fibroepithelial and high-risk BCC growth patterns. A simplified classification system comprised of superficial, fibroepithelial, nodular and infiltrative subtypes would increase interobserver precision and facilitate clinical decision-making.

Through careful clinicopathologic correlation, we identified 37 metastatic melanomas in the skin, all of which had intraepidermal components. These were compared with 43 microscopically similar primary melanomas with a predetermined panel of immunostains in general use in surgical pathology, including bcl-2 protein, mutant p53 protein, Ki-67 (MIB-1), proliferating cell nuclear antigen (PCNA), alpha-isoform actin, and CD117 (c-kit protein). There was no significant difference in bcl-2 or alpha-isoform actin staining patterns of primary vs secondary cutaneous melanomas. The expression of Ki-67 generally was higher in metastatic melanomas than in primary lesions, and the same was true of mutant p53 protein labeling; however, some overlap was observed. CD117 staining was retained in 65% of metastatic melanomas (24/37) when they originated from ocular primary tumors; nevertheless, that marker was lost in virtually all of the other metastatic melanocytic neoplasms, whereas primary melanomas demonstrated consistent reactivity for c-kit protein. Although they are not definitive, these trends in immunoreactivity could facilitate the process of distinguishing the multiple primary melanoma syndrome from melanomatous metastases to the skin. That undertaking is best approached with circumspection, because clinicopathologic discriminators for this diagnostic separation are still imperfect.

No abstract

AMR and BMR metrics are potential performance indicators that can measure pathologist uncertainty, identify diagnostic drift and provide a surrogate measure of the relative risk level of laboratory patient populations. If applied to multiple laboratories, AMR and BMR metrics could help inform physicians' choice of dermatopathology laboratory and provide a method for comparative analysis between laboratories.