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.

Precursors of endometrial and ovarian carcinoma.

This review discusses precursor lesions of endometrial and ovarian carcinoma with an emphasis on the unique molecular alterations that have led to the development of binary classification schemes for tumors of both the endometrium and ovary. While such a system is well established for endometrial carcinoma, only recently has a binary classification scheme been proposed for ovarian carcinoma. For both, the morphologic and molecular genetic-defining characteristics of their respective precursor lesions are described in detail. Furthermore, similarities and differences of the precursor lesions of specific tumors of these two genital tract organs are also addressed with a brief discussion of the clinical implications of their diagnosis.

Diagnosis and subclassification of hydatidiform moles using p57 immunohistochemistry and molecular genotyping: validation and prospective analysis in routine and consultation practice settings with development of an algorithmic approach.

Distinction of hydatidiform moles (HM) from nonmolar specimens and subclassification of HMs as complete hydatidiform mole (CHM), partial hydatidiform mole (PHM), or early CHM (eCHM) are important for clinical practice and investigational studies but diagnosis based solely on morphology suffers from poor interobserver reproducibility. Recent studies have demonstrated the use of p57 immunostaining and molecular genotyping for improving diagnosis of HMs. After performing a validation study of both techniques on 24 archival products of conception specimens (7 CHMs, 8 PHMs, 9 nonmolar), we prospectively analyzed 42 cases, largely obtained from a gynecologic pathology consultation practice, for which there was any consideration of a diagnosis of HM. After satisfactory experience with prospective cases, a modified approach was adopted, with p57 immunostaining used in conjunction with morphology to triage cases for molecular genotyping. Final diagnoses for the prospective cases based on combined morphology and ancillary testing were 24 CHMs (including 7 eCHMs), 7 PHMs, and 11 nonmolar specimens. P57 immunostaining, performed on all 66 cases, was negative in all CHMs, with the exception of 1 case of molecularly confirmed CHM with diffuse p57 expression, and positive in all PHMs and nonmolar specimens, with the exception of 3 cases of molecularly confirmed PHMs with an equivocal extent of p57 expression. Molecular genotyping of 51 cases (24 validation, 27 prospective) yielded data consistent with p57 results in the 47 cases with unequivocal p57 expression patterns and was used to establish the diagnoses for the 4 cases with aberrant or equivocal p57 results. All 17 genotyped CHMs demonstrated androgenetic diploidy, including the CHM with retained p57 expression; this case also demonstrated trisomy of chromosome 11 (retained maternal allele), accounting for the aberrant p57 expression. The remaining 14 CHMs were diagnosed by morphology and negative p57 results alone. All 15 PHMs demonstrated diandric triploidy. All genotyped nonmolar specimens demonstrated biparental diploidy. This study validates p57 immunostaining as a prospectively applicable triage assay for the diagnosis of CHMs based on morphology and a negative p57 result. Molecular genotyping is validated as a method to confirm a diagnosis of CHM by demonstrating androgenetic diploidy and to resolve p57-positive cases into diandric triploid PHMs, biparental diploid nonmolar specimens, and the rare CHM with aberrant p57 expression.

Molecular genotyping of hydatidiform moles: analytic validation of a multiplex short tandem repeat assay.

Distinction of hydatidiform moles from non-molar (NM) specimens, as well as their subclassification as complete (CHM) versus partial hydatidiform moles (PHM), is important for clinical management and accurate risk assessment for persistent gestational trophoblastic disease. Because diagnosis of hydatidiform moles based solely on morphology suffers from poor interobserver reproducibility, a variety of ancillary techniques have been developed to improve diagnosis. Immunohistochemical assessment of the paternally imprinted, maternally expressed p57 gene can identify CHMs (androgenetic diploidy) by their lack of p57 expression, but cannot distinguish PHMs (diandric monogynic triploidy) from NMs (biparental diploidy). Short tandem repeat genotyping can identify the parental source of polymorphic alleles and thus discern androgenetic diploidy, diandric triploidy, and biparental diploidy, which allows for specific diagnosis of CHMs, PHMs, and NMs, respectively. In this study, a retrospectively collected set of morphologically typical CHMs (n = 8), PHMs (n = 10), and NMs (n = 12) was subjected to an analytic validation study of both short tandem repeat genotyping and p57 immunohistochemistry. Several technical and biological problems resulted in data that were difficult to interpret. To avoid these pitfalls, we have developed an algorithm with quantitative guidelines for the interpretation of short tandem repeat genotyping data.

Complete hydatidiform mole with retained maternal chromosomes 6 and 11.

Distinction of hydatidiform moles from nonmolar specimens and their subclassification as complete hydatidiform mole (CHM) versus partial hydatidiform mole (PHM) are important for clinical practice and investigational studies to refine ascertainment of risk of persistent gestational trophoblastic disease which differs among these entities. Immunohistochemical analysis of p57 expression, a paternally imprinted maternally expressed gene on 11p15.5, and molecular genotyping are useful for improving diagnosis. CHMs are characterized by androgenetic diploidy, with the loss of p57 expression owing to lack of maternal DNA. Loss of p57 expression distinguishes CHMs from both PHMs (diandric triploidy) and nonmolar specimens (biparental diploidy) which retain expression. In the process of evaluating molar specimens in our laboratory with p57 immunohistochemistry and molecular genotyping, we identified a morphologically typical androgenetic diploid CHM with aberrant diffuse p57 expression. Molecular genotyping by short tandem repeat markers and genome-wide copy number analysis by single nucleotide polymorphism array established androgenetic diploidy with retained maternal copies of chromosomes 6 and 11, with aberrant p57 expression attributable to the latter. This case, only the second reported to date, illustrates the value of combined traditional pathologic and ancillary molecular techniques for refined diagnosis of molar specimens. Specimens with morphologic features suggestive of CHM yet retaining p57 expression should be subjected to molecular genotyping to establish a definitive diagnosis because misclassification as PHM underestimates the risk of persistent gestational trophoblastic disease. We recommend use of p57 immunohistochemistry and molecular genotyping to evaluate all products of conception specimens for which there is any consideration of a diagnosis of hydatidiform mole. Genome-wide analysis has the potential to assist in localizing imprinted genes critical for determining the morphologic and behavioral phenotypes of hydatidiform moles.