Diagnostic 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.

Machine Learning Method Reveals Hidden Strong Metal-Support Interaction in Microscopy Datasets.

Forming an ultra-thin, permeable encapsulation oxide-support layer on a metal catalyst surface is considered an effective strategy for achieving a balance between high stability and high activity in heterogenous catalysts. The success of such a design relies not only on the thickness, ideally one to two atomic layers thick, but also on the morphology and chemistry of the encapsulation layer. Reliably identifying the presence and chemical nature of such a trace layer has been challenging. Electron energy-loss spectroscopy (EELS) performed in a scanning transmission electron microscope (STEM), the primary technique utilized for such studies, is limited by a weak signal on overlayers when using conventional analysis methods, often leading to misinterpreted or missed information. Here, a robust, unsupervised machine learning data analysis method is developed to reveal trace encapsulation layers that are otherwise overlooked in STEM-EELS datasets. This method provides a reliable tool for analyzing encapsulation of catalysts and is generally applicable to any spectroscopic analysis of materials and devices where revealing a trace signal and its spatial distribution is challenging.

Desmoplastic trichoepithelioma.

BACKGROUND: Desmoplastic trichoepithelioma (DTE) is an uncommon adnexal tumor usually found on the face of young women. OBJECTIVE: We sought to describe the clinical and histologic characteristics of DTE and discuss management strategies for these tumors. METHODS: We conducted a retrospective case series and review of the literature. RESULTS: A series of 17 cases of DTE is reported. Of our patients, 82% were female and half of all these cases occurred on the cheek. Unlike previous reports, the patients in our study were slightly older, with 53% older than 51 years and 71% between the ages of 31 and 60 years at the time of surgery (mean age 49 years, median age 52 years, range 14-81 years). Approximately 38% of the tumors had been present for 1 to 2 years before presentation. The average size of the tumors at the time of surgery was 0.8 x 0.6 cm. All cases were treated with Mohs micrographic surgery. To date, none of the tumors have recurred. LIMITATIONS: This is a small case series. The referral patterns of our predominantly Mohs micrographic surgery clinic might further bias this study. CONCLUSION: DTE is a benign tumor that has a predilection for the face. With its rapid growth, aggressive histologic features that may be confused with basal cell carcinoma, and tendency to arise in cosmetically and functionally sensitive areas, these tumors should be removed in a manner that assures clear surgical margins, such as Mohs micrographic surgery.