Digital Whole Slide Imaging Compared With Light Microscopy for Primary Diagnosis in Surgical Pathology.

CONTEXT.­: The adoption of digital capture of pathology slides as whole slide images (WSI) for educational and research applications has proven utility. OBJECTIVE.­: To compare pathologists' primary diagnoses derived from WSI versus the standard microscope. Because WSIs differ in format and method of observation compared with the current standard glass slide microscopy, this study is critical to potential clinical adoption of digital pathology. DESIGN.­: The study enrolled a total of 2045 cases enriched for more difficult diagnostic categories and represented as 5849 slides were curated and provided for diagnosis by a team of 19 reading pathologists separately as WSI or as glass slides viewed by light microscope. Cases were reviewed by each pathologist in both modalities in randomized order with a minimum 31-day washout between modality reads for each case. Each diagnosis was compared with the original clinical reference diagnosis by an independent central adjudication review. RESULTS.­: The overall major discrepancy rates were 3.64% for WSI review and 3.20% for manual slide review diagnosis methods, a difference of 0.44% (95% CI, -0.15 to 1.03). The time to review a case averaged 5.20 minutes for WSI and 4.95 minutes for glass slides. There was no specific subset of diagnostic category that showed higher rates of modality-specific discrepancy, though some categories showed greater discrepancy than others in both modalities. CONCLUSIONS.­: WSIs are noninferior to traditional glass slides for primary diagnosis in anatomic pathology.

Sclerosing epithelioid mesenchymal neoplasm of the pancreas - a proposed new entity.

We have encountered pancreatic tumors with unique histologic features, which do not conform to any of the known tumors of the pancreas or other anatomical sites. We aimed to define their clinicopathologic features and whether they are characterized by recurrent molecular signatures. Eight cases were identified; studied histologically and by immunohistochemistry. Selected cases were also subjected to whole-exome sequencing (WES; n = 4), RNA-sequencing (n = 6), Archer FusionPlex assay (n = 5), methylation profiling using the Illumina MethylationEPIC (850k) array platform (n = 6), and TERT promoter sequencing (n = 5). Six neoplasms occurred in females. The mean age was 43 years (range: 26-75). Five occurred in the head/neck of the pancreas. All patients were treated surgically; none received neoadjuvant/adjuvant therapy. All patients are free of disease after 53 months of median follow-up (range: 8-94). The tumors were well-circumscribed, and the median size was 1.8 cm (range: 1.3-5.8). Microscopically, the unencapsulated tumors had a geographic pattern of epithelioid cell nests alternating with spindle cell fascicles. Some areas showed dense fibrosis, in which enmeshed tumor cells imparted a slit-like pattern. The predominant epithelioid cells had scant cytoplasm and round-oval nuclei with open chromatin. The spindle cells displayed irregular, hyperchromatic nuclei. Mitoses were rare. No lymph node metastases were identified. All tumors were positive for vimentin, CD99 and cytokeratin (patchy), while negative for markers of solid pseudopapillary neoplasm, neuroendocrine, acinar, myogenic/rhabdoid, vascular, melanocytic, or lymphoid differentiation, gastrointestinal stromal tumor as well as MUC4. Whole-exome sequencing revealed no recurrent somatic mutations or amplifications/homozygous deletions in any known oncogenes or tumor suppressor genes. RNA-sequencing and the Archer FusionPlex assay did not detect any recurrent likely pathogenic gene fusions. Single sample gene set enrichment analysis revealed that these tumors display a likely mesenchymal transcriptomic program. Unsupervised analysis (t-SNE) of their methylation profiles against a set of different mesenchymal neoplasms demonstrated a distinct methylation pattern. Here, we describe pancreatic neoplasms with unique morphologic/immunophenotypic features and a distinct methylation pattern, along with a lack of abnormalities in any of key genetic drivers, supporting that these neoplasms represent a novel entity with an indolent clinical course. Given their mesenchymal transcriptomic features, we propose the designation of "sclerosing epithelioid mesenchymal neoplasm" of the pancreas.

Bioremediation Strategies Aimed at Stimulating Chlorinated Solvent Dehalogenation Can Lead to Microbially-Mediated Toluene Biogenesis.

In situ bioremediation practices that include subsurface addition of fermentable electron donors to stimulate reductive dechlorination by anaerobic bacteria have become widely employed to combat chlorinated solvent contamination in groundwater. At a contaminated site located near Baton Rouge, Louisiana (USA), toluene was transiently observed in groundwater at concentrations that sometimes far exceeded the US drinking water maximum contaminant level (MCL) of 1 mg/L after a fermentable substrate (agricultural feed grade cane molasses) was injected into the subsurface with the intent of providing electron donors for reductive dechlorination. Here, we present data that demonstrate that indigenous microorganisms can biologically produce toluene by converting phenylacetic acid, phenylalanine, phenyllactate, and phenylpyruvate to toluene. When grown in defined medium with phenylacetic acid at concentrations ≤350 mg/L, the molar ratio between toluene accumulated and phenylacetic acid supplied was highly correlated ( R2 ≥ 0.96) with a toluene yield exceeding 0.9:1. Experiments conducted using 13C labeled compounds (phenylacetic acid-2-13C and l-phenylalanine-3-13C) resulted in production of toluene-α-13C, confirming that toluene was synthesized from these precursors by two independently developed enrichment cultures. Results presented here suggest that monitoring of aromatic hydrocarbons is warranted during enhanced bioremediation activities where electron donors are introduced to stimulate anaerobic biotransformation of chlorinated solvents.