Principles of Analytic Validation of Immunohistochemical Assays: Guideline Update.

CONTEXT.­: In 2014, the College of American Pathologists developed an evidence-based guideline to address analytic validation of immunohistochemical assays. Fourteen recommendations were offered. Per the National Academy of Medicine standards for developing trustworthy guidelines, guidelines should be updated when new evidence suggests modifications. OBJECTIVE.­: To assess evidence published since the release of the original guideline and develop updated evidence-based recommendations. DESIGN.­: The College of American Pathologists convened an expert panel to perform a systematic review of the literature and update the original guideline recommendations using the Grading of Recommendations Assessment, Development and Evaluation approach. RESULTS.­: Two strong recommendations, 1 conditional recommendation, and 12 good practice statements are offered in this updated guideline. They address analytic validation or verification of predictive and nonpredictive assays, and recommended revalidation procedures following changes in assay conditions. CONCLUSIONS.­: While many of the original guideline statements remain similar, new recommendations address analytic validation of assays with distinct scoring systems, such as programmed death receptor-1 and analytic verification of US Food and Drug Administration approved/cleared assays; more specific guidance is offered for validating immunohistochemistry performed on cytology specimens.

Molecular Biomarker Testing for the Diagnosis of Diffuse Gliomas.

CONTEXT.­: The diagnosis and clinical management of patients with diffuse gliomas (DGs) have evolved rapidly over the past decade with the emergence of molecular biomarkers that are used to classify, stratify risk, and predict treatment response for optimal clinical care. OBJECTIVE.­: To develop evidence-based recommendations for informing molecular biomarker testing for pediatric and adult patients with DGs and provide guidance for appropriate laboratory test and biomarker selection for optimal diagnosis, risk stratification, and prediction. DESIGN.­: The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. A systematic review of literature was conducted to address the overarching question, "What ancillary tests are needed to classify DGs and sufficiently inform the clinical management of patients?" Recommendations were derived from quality of evidence, open comment feedback, and expert panel consensus. RESULTS.­: Thirteen recommendations and 3 good practice statements were established to guide pathologists and treating physicians on the most appropriate methods and molecular biomarkers to include in laboratory testing to inform clinical management of patients with DGs. CONCLUSIONS.­: Evidence-based incorporation of laboratory results from molecular biomarker testing into integrated diagnoses of DGs provides reproducible and clinically meaningful information for patient management.

Validating Whole Slide Imaging Systems for Diagnostic Purposes in Pathology.

CONTEXT.­: The original guideline, "Validating Whole Slide Imaging for Diagnostic Purposes in Pathology," was published in 2013 and included 12 guideline statements. The College of American Pathologists convened an expert panel to update the guideline following standards established by the National Academies of Medicine for developing trustworthy clinical practice guidelines. OBJECTIVE.­: To assess evidence published since the release of the original guideline and provide updated recommendations for validating whole slide imaging (WSI) systems used for diagnostic purposes. DESIGN.­: An expert panel performed a systematic review of the literature. Frozen sections, anatomic pathology specimens (biopsies, curettings, and resections), and hematopathology cases were included. Cytology cases were excluded. Using the Grading of Recommendations Assessment, Development, and Evaluation approach, the panel reassessed and updated the original guideline recommendations. RESULTS.­: Three strong recommendations and 9 good practice statements are offered to assist laboratories with validating WSI digital pathology systems. CONCLUSIONS.­: Systematic review of literature following release of the 2013 guideline reaffirms the use of a validation set of at least 60 cases, establishing intraobserver diagnostic concordance between WSI and glass slides and the use of a 2-week washout period between modalities. Although all discordances between WSI and glass slide diagnoses discovered during validation need to be reconciled, laboratories should be particularly concerned if their overall WSI-glass slide concordance is less than 95%.

Collection and Handling of Thoracic Small Biopsy and Cytology Specimens for Ancillary Studies: Guideline From the College of American Pathologists in Collaboration With the American College of Chest Physicians, Association for Molecular Pathology, American Society of Cytopathology, American Thoracic Society, Pulmonary Pathology Society, Papanicolaou Society of Cytopathology, Society of Interventional Radiology, and Society of Thoracic Radiology.

CONTEXT.­: The need for appropriate specimen use for ancillary testing has become more commonplace in the practice of pathology. This, coupled with improvements in technology, often provides less invasive methods of testing, but presents new challenges to appropriate specimen collection and handling of these small specimens, including thoracic small biopsy and cytology samples. OBJECTIVE.­: To develop a clinical practice guideline including recommendations on how to obtain, handle, and process thoracic small biopsy and cytology tissue specimens for diagnostic testing and ancillary studies. METHODS.­: The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. Core needle biopsy, touch preparation, fine-needle aspiration, and effusion specimens with thoracic diseases including malignancy, granulomatous process/sarcoidosis, and infection (eg, tuberculosis) were deemed within scope. Ancillary studies included immunohistochemistry and immunocytochemistry, fluorescence in situ hybridization, mutational analysis, flow cytometry, cytogenetics, and microbiologic studies routinely performed in the clinical pathology laboratory. The use of rapid on-site evaluation was also covered. RESULTS.­: Sixteen guideline statements were developed to assist clinicians and pathologists in collecting and processing thoracic small biopsy and cytology tissue samples. CONCLUSIONS.­: Based on the systematic review and expert panel consensus, thoracic small specimens can be handled and processed to perform downstream testing (eg, molecular markers, immunohistochemical biomarkers), core needle and fine-needle techniques can provide appropriate cytologic and histologic specimens for ancillary studies, and rapid on-site cytologic evaluation remains helpful in appropriate triage, handling, and processing of specimens.

Quantitative Image Analysis of Human Epidermal Growth Factor Receptor 2 Immunohistochemistry for Breast Cancer: Guideline From the College of American Pathologists.

CONTEXT.­: Advancements in genomic, computing, and imaging technology have spurred new opportunities to use quantitative image analysis (QIA) for diagnostic testing. OBJECTIVE.­: To develop evidence-based recommendations to improve accuracy, precision, and reproducibility in the interpretation of human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) for breast cancer where QIA is used. DESIGN.­: The College of American Pathologists (CAP) convened a panel of pathologists, histotechnologists, and computer scientists with expertise in image analysis, immunohistochemistry, quality management, and breast pathology to develop recommendations for QIA of HER2 IHC in breast cancer. A systematic review of the literature was conducted to address 5 key questions. Final recommendations were derived from strength of evidence, open comment feedback, expert panel consensus, and advisory panel review. RESULTS.­: Eleven recommendations were drafted: 7 based on CAP laboratory accreditation requirements and 4 based on expert consensus opinions. A 3-week open comment period received 180 comments from more than 150 participants. CONCLUSIONS.­: To improve accurate, precise, and reproducible interpretation of HER2 IHC results for breast cancer, QIA and procedures must be validated before implementation, followed by regular maintenance and ongoing evaluation of quality control and quality assurance. HER2 QIA performance, interpretation, and reporting should be supervised by pathologists with expertise in QIA.

Human Papillomavirus Testing in Head and Neck Carcinomas: Guideline From the College of American Pathologists.

Context Human papillomavirus (HPV) is a major cause of oropharyngeal squamous cell carcinomas, and HPV (and/or surrogate marker p16) status has emerged as a prognostic marker that significantly impacts clinical management. There is no current consensus on when to test oropharyngeal squamous cell carcinomas for HPV/p16 or on which tests to choose. Objective To develop evidence-based recommendations for the testing, application, interpretation, and reporting of HPV and surrogate marker tests in head and neck carcinomas. Design The College of American Pathologists convened a panel of experts in head and neck and molecular pathology, as well as surgical, medical, and radiation oncology, to develop recommendations. A systematic review of the literature was conducted to address 6 key questions. Final recommendations were derived from strength of evidence, open comment period feedback, and expert panel consensus. Results The major recommendations include (1) testing newly diagnosed oropharyngeal squamous cell carcinoma patients for high-risk HPV, either from the primary tumor or from cervical nodal metastases, using p16 immunohistochemistry with a 70% nuclear and cytoplasmic staining cutoff, and (2) not routinely testing nonsquamous oropharyngeal carcinomas or nonoropharyngeal carcinomas for HPV. Pathologists are to report tumors as HPV positive or p16 positive. Guidelines are provided for testing cytologic samples and handling of locoregional and distant recurrence specimens. Conclusions Based on the systematic review and on expert panel consensus, high-risk HPV testing is recommended for all new oropharyngeal squamous cell carcinoma patients, but not routinely recommended for other head and neck carcinomas.

Evaluation of Testing of Acute Leukemia Samples: Survey Result From the College of American Pathologists.

CONTEXT: - The classification and prognosis determination in acute leukemia (AL) are complex and it is unclear what testing is being performed in practice. OBJECTIVE: - To survey physicians describing their current practice of test ordering in the diagnosis of AL. DESIGN: - In anticipation of a guideline by the College of American Pathologists (CAP) and the American Society for Hematology on laboratory testing needed for the initial workup of AL, a baseline survey was designed by an expert panel from CAP. Members of professional societies were asked to describe their current practice of test ordering. RESULTS: - Two hundred ninety-four responses were received with 258 respondents analyzed after the first qualifying survey question regarding initial diagnosis of AL. One hundred seventy-six of 249 respondents (70.7%) were board-certified hematopathologists. Flow cytometry and karyotype analysis were routinely performed for acute myeloid leukemia (AML) (99.1% [232 of 234] and 96.2% [225 of 234], respectively) and acute lymphoblastic leukemia (ALL) (98.3% [229 of 233] and 96.6% [225 of 233], respectively). In addition, fluorescence in situ hybridization studies were routinely performed by 81.2% (190 of 234) of respondents for AML and 85.0% (198 of 233) of respondents for ALL; other molecular studies were performed by 78.2% (183) for AML and 54.9% (128) for ALL; immunohistochemistry by 44.9% (105) for AML and 47.6% (111) for ALL; and cytochemistry by 24.8% (58) for AML and 14.2% (33) for ALL. CONCLUSIONS: - While flow cytometry and karyotyping are routinely reported as being performed for the diagnosis of AL, there is marked variation in the reporting of testing patterns for other genetic studies, immunohistochemistry, and cytochemistry.

Initial Diagnostic Workup of Acute Leukemia: Guideline From the College of American Pathologists and the American Society of Hematology.

CONTEXT: - A complete diagnosis of acute leukemia requires knowledge of clinical information combined with morphologic evaluation, immunophenotyping and karyotype analysis, and often, molecular genetic testing. Although many aspects of the workup for acute leukemia are well accepted, few guidelines have addressed the different aspects of the diagnostic evaluation of samples from patients suspected to have acute leukemia. OBJECTIVE: - To develop a guideline for treating physicians and pathologists involved in the diagnostic and prognostic evaluation of new acute leukemia samples, including acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemias of ambiguous lineage. DESIGN: - The College of American Pathologists and the American Society of Hematology convened a panel of experts in hematology and hematopathology to develop recommendations. A systematic evidence review was conducted to address 6 key questions. Recommendations were derived from strength of evidence, feedback received during the public comment period, and expert panel consensus. RESULTS: - Twenty-seven guideline statements were established, which ranged from recommendations on what clinical and laboratory information should be available as part of the diagnostic and prognostic evaluation of acute leukemia samples to what types of testing should be performed routinely, with recommendations on where such testing should be performed and how the results should be reported. CONCLUSIONS: - The guideline provides a framework for the multiple steps, including laboratory testing, in the evaluation of acute leukemia samples. Some aspects of the guideline, especially molecular genetic testing in acute leukemia, are rapidly changing with new supportive literature, which will require on-going updates for the guideline to remain relevant.

Bone Marrow Synoptic Reporting for Hematologic Neoplasms: Guideline From the College of American Pathologists Pathology and Laboratory Quality Center.

CONTEXT: -There is ample evidence from the solid tumor literature that synoptic reporting improves accuracy and completeness of relevant data. No evidence-based guidelines currently exist for synoptic reporting for bone marrow samples. OBJECTIVE: -To develop evidence-based recommendations to standardize the basic components of a synoptic report template for bone marrow samples. DESIGN: -The College of American Pathologists Pathology and Laboratory Quality Center convened a panel of experts in hematopathology to develop recommendations. A systematic evidence review was conducted to address 5 key questions. Recommendations were derived from strength of evidence, open comment feedback, and expert panel consensus. RESULTS: -Nine guideline statements were established to provide pathology laboratories with a framework by which to develop synoptic reporting templates for bone marrow samples. The guideline calls for specific data groups in the synoptic section of the pathology report; provides a list of evidence-based parameters for key, pertinent elements; and addresses ancillary testing. CONCLUSION: -A framework for bone marrow synoptic reporting will improve completeness of the final report in a manner that is clear, succinct, and consistent among institutions.

Uniform Labeling of Blocks and Slides in Surgical Pathology: Guideline From the College of American Pathologists Pathology and Laboratory Quality Center and the National Society for Histotechnology.

CONTEXT: The labeling of paraffin blocks and microscopic glass slides in the practice of surgical pathology varies from institution to institution and introduces potential risk of preanalytic error. Currently there are no evidence-based guidelines regarding the uniform labeling of these materials. OBJECTIVE: To develop recommendations that will address the need for adequate patient identification and provide a consistent method of identifying slides originating from a particular block. DESIGN: - The College of American Pathologists Pathology and Laboratory Quality Center and the National Society for Histotechnology convened a panel of pathologists and histotechnologists with expertise in histology laboratory quality practices to develop labeling recommendations. A systematic evidence review was conducted to address 6 main key questions. Recommendations were derived from strength of evidence, open comment feedback, and expert panel consensus. RESULTS: Twelve guideline statements were established to assist pathology laboratories in developing standardized block and slide labeling practices. These guidelines call for the use of 2 patient identifiers, 1 of which includes the accession number and case type, on all paraffin blocks and slides. Recommendations were also developed to address the order and format in which identifying elements should appear. CONCLUSIONS: Uniform labeling of paraffin blocks and slides derived from patient specimens will provide an important enhancement to patient safety by assuring that all preparations derived from a patient's tissue can be uniquely and unambiguously linked to that patient. Adoption of standardized practices additionally will improve patient care by facilitating interpretation of histologic sections when they are referred in consultation to a second institution.

Cytology of spontaneous nipple discharge--is it worth it? Performance of nipple discharge preparations in the College of American Pathologists Interlaboratory Comparison Program in Nongynecologic Cytopathology.

CONTEXT: The usefulness of spontaneous nipple discharge analysis is controversial. Nipple discharge preparations are rare in clinical practice and malignant cases are exceptional. The College of American Pathologists Interlaboratory Comparison Program in Nongynecologic Cytopathology has included nipple discharge preparations since its inception. OBJECTIVES: To evaluate participant responses in the College of American Pathologists Interlaboratory Comparison Program in Nongynecologic Cytopathology to assess the accuracy of cytologic interpretation of nipple discharge preparation. DESIGN: General diagnostic category (benign, suspicious, malignant), participant type (pathologist, cytotechnologist), stain (Papanicolaou, modified Giemsa), and program year (2005-2009) were analyzed using χ(2) and a nonlinear mixed model for slide factor correlation structure. RESULTS: Of 2506 responses, 1280 (51%) were malignant, 171 (7%) were papillary, and 1055 (42%) were benign. There were 222 discordant general category responses with a false-positive/suspicious rate of 12.8% and a false-negative rate of 3.4%. The most common false-negative diagnosis was mastitis/abscess (125 of 1272 responses; 9.8%). The most common false-positive response was papillary lesion (26 of 457 responses; 5.7%). There were no differences between stains or years. Cytotechnologists performed better than pathologists; pathologists had a higher false-negative rate than cytotechnologists (15.3% versus 7.9%, P < .001). CONCLUSIONS: There is poor accuracy in evaluating nipple discharge preparation in the College of American Pathologists Interlaboratory Comparison Program in Nongynecologic Cytopathology. If the findings in the program parallel clinical practice, nipple discharge preparations may adversely impact patient care. A benign nipple discharge cytologic diagnosis does not exclude malignancy, and the false-positive/suspicious rate requires confirmation of a malignant nipple discharge prior to definitive patient management.