Cytopathology fellowship recruitment: historical context, current state, and future considerations.

Fellowship recruitment and retention of a skilled workforce is one of the biggest challenges that not only cytopathology is facing but that the field of pathology in general is being confronted with. There have long been issues with the fellowship recruitment process for both applicants and fellowship directors, including pressure to move the application process earlier and earlier and frustrations stemming from applicants needing to determine different individual timelines and program requirements. The unified timeline for fellowship recruitment was established as an attempt to standardize the recruitment process and to address the key issues of the push for earlier and earlier decision-making, which placed significant anxiety on trainees, as well as the burden on programs of more unexpected openings. While institution of the unified timeline has had many successes, there have been problems as well. Here, we discuss the multifaceted and intertwined factors that affect fellowship recruitment with a review of the historical context and the current setting and with an eye towards future directions. In the end, the issues we are currently facing are complex and there is likely no perfect solution to fixing an inherently broken system. However, the ultimate goal should be in better supporting our trainees' development and promoting a more fair and equitable recruitment process. Only by working together can we optimize the process for both applicants and programs alike.

Using American Type Culture Collection Cell Lines to Evaluate Interlaboratory Variables for Estrogen Receptor and Human Epidermal Growth Factor Receptor 2 Immunostaining.

CONTEXT.­: Most laboratories currently use patient tissues for validating immunohistochemical stains. OBJECTIVE.­: To explore advantages of using cell lines with known antigenicity as a validation method. DESIGN.­: Five American Type Culture Collection (ATCC) cell lines with known negative, low positive, and moderate to strong estrogen receptor (ER) expression as well as negative, equivocal, and positive human epidermal growth factor receptor 2 (HER2) expression were cultured and made into cell blocks. One block from each cell line was fixed in formalin and another in ethanol before cell block preparation. Two sets of paired unstained slides from each block were sent to 10 different laboratories for HER2 and ER staining to be stained on runs from different days according to each laboratory's defined protocol. RESULTS.­: The 10 study participants evaluated 40 slides in a blinded fashion. For ER expression, all 80 interpretations for the ER strong and moderate positive cell lines had the target ER-positive result, and 74 of 80 ER-negative cell lines (92.5%) had agreement with the intended negative result. The ER low positive cell line showed varied but positive expression among all observers. The HER2 (3+)-positive cell lines yielded a target interpretation of 3+ in 65 of 80 interpretations (81.2%). For the HER2-negative cell line 69 of 78 interpretations (88.5%) were consistent with the target response (0 or 1+). No significant variation was observed between the ethanol- and non-ethanol-exposed cell lines, or between runs by the same laboratory. Variation from target results clustered within laboratories. CONCLUSIONS.­: This study indicates that variability between laboratories can be identified by using cell lines for quantitative or semiquantitative immunohistochemistry when using cultured cell lines of known antigenicity. These cell lines could potentially play a role in aiding anatomic pathology laboratories in validating immunohistochemistry tests for formalin- and ethanol-fixed tissues.

Cytologic features of metastatic epithelioid uterine leiomyosarcoma to the pancreas.

Although uterine leiomyosarcoma (ULMS) is a rare disease, it accounts for a significant proportion uterine cancer-related deaths due to frequent metastasis and chemoresistance. The WHO currently recognizes the conventional (spindle), myxoid, and epithelioid variants of ULMS, the latter of which is the rarest, least understood, and cited as clinically more aggressive than the other variants. Descriptions of the histologic features of epithelioid ULMS are extremely limited, and are absent from the cytology literature which has only published descriptions of conventional ULMS or epithelioid variants of other LMS primaries. Therefore, we present a unique case of metastatic epithelioid ULMS to an unusual location, the pancreas, along with its cytologic features on endoscopic ultrasound-guided fine needle aspiration not previously described including pseudoglandular arrangements, scant cytoplasm, and frequent molding.

Correction: Role of caveolin-1 as a biomarker for radiation resistance and tumor aggression in lung cancer.

[This corrects the article DOI: 10.1371/journal.pone.0258951.].

Performance of specific morphologic features in distinguishing low-grade squamous intraepithelial lesions from high-grade squamous intraepithelial lesions in borderline cases: a College of American Pathologists Cytopathology Committee multiobserver study.

INTRODUCTION: Distinguishing between low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL) can be difficult on certain Papanicolaou (Pap) tests, hindering interobserver concordance. We investigated the variables influencing the interpretation of LSIL versus HSIL in Pap test slides rejected from the College of American Pathologists PAP education program. MATERIALS AND METHODS: Eleven cytologists, who were unaware of the reference interpretation, examined 21 Pap slides (11 submitted as LSIL and 10 as HSIL) rejected from the PAP education program and recorded the number of LSIL cells, HSIL cells, keratinized dysplastic cells, LSIL clusters with mixed HSIL cells, atypical squamous metaplasia, atypical glandular cells, the presence of inflammation or infectious organisms, and the overall interpretation (LSIL or HSIL). We evaluated the significance of these 11 variables using a nonlinear mixed model analysis. RESULTS: LSIL had greater concordance (92 of 121 responses; 76.0% concordance) than HSIL (68 of 110 responses; 61.8% concordance; P < 0.001). The only predictors of misclassified cases were the number of atypical squamous metaplastic cells and the number of HSIL cells (P < 0.001). The more of these cells identified, the more likely the reviewers were to classify the slide as HSIL. The reproducibility of the diagnosis was fair (Gwet's agreement coefficient, 0.33). CONCLUSIONS: Interobserver reproducibility is a challenge for a subset of cases with features intermediate between LSIL and HSIL. Atypical squamous metaplasia and dysplastic nuclei with a nuclear/cytoplasmic ratio greater than one half of the cell volume (HSIL) present on a Pap test influenced the likelihood that a reviewer would interpret the case as HSIL rather than LSIL.

Metastatic mesonephric-like endometrial adenocarcinoma diagnosed on transbronchial needle aspirate cytology.

Mesonephric-like adenocarcinoma is a relatively rare neoplasm with morphology similar to mesonephric adenocarcinoma but unassociated with mesonephric remnants. Its relatively recent description and rarity make it difficult to diagnose, but it has a high rate of distant metastasis, making distinction from endometrioid carcinoma important. Descriptions of its cytologic features are particularly limited. We describe a case of mesonephric-like adenocarcinoma diagnosed on transbronchial needle aspiration of the lung, that had been misdiagnosed as endometrioid endometrial adenocarcinoma on a prior hysterectomy. We discuss the characteristic cyto and histomorphology, immunoprofile, molecular alterations, and clinical significance of this uncommon tumor.

Role of caveolin-1 as a biomarker for radiation resistance and tumor aggression in lung cancer.

Radiation therapy plays a major role in the treatment of lung cancer patients. However, cancer cells develop resistance to radiation. Tumor radioresistance is a complex multifactorial mechanism which may be dependent on DNA damage and repair, hypoxic conditions inside tumor microenvironment, and the clonal selection of radioresistant cells from the heterogeneous tumor site, and it is a major cause of treatment failure in non-small cell lung cancer (NSCLC). In the present investigation caveolin-1 (CAV-1) has been observed to be highly expressed in radiation resistant A549 lung cancer cells. CRISPR-Cas9 knockout of CAV-1 reverted the cells to a radio sensitive phenotype. In addition, CAV-1 overexpression in parental A549 cells, led to radiation resistance. Further, gene expression analysis of A549 parental, radiation resistant, and caveolin-1 overexpressed cells, exhibited overexpression of DNA repair genes RAD51B, RAD18, SOX2 cancer stem cell marker, MMPs, mucins and cytoskeleton proteins in resistant and caveolin-1 over expressed A549 cells, as compared to parental A549 cells. Bioinformatic analysis shows upregulation of BRCA1, Nuclear Excision DNA repair, TGFB and JAK/STAT signaling pathways in radioresistant and caveolin-1 overexpressed cells, which may functionally mediate radiation resistance. Immunohistochemistry data demonstrated heterogeneous expression of CAV-1 gene in human lung cancer tissues, which was analogous to its enhanced expression in human lung cancer cell line model and mouse orthotopic xenograft lung cancer model. Also, TCGA PanCancer clinical studies have demonstrated amplification, deletions and missense mutation in CAV-1 gene in lung cancer patients, and that CAV-1 alteration has been linked to poor prognosis, and poor survival in lung cancer patients. Interestingly, we have also optimized ELISA assay to measure caveolin-1 protein in the blood of A549 radiation resistant human xenograft preclinical mouse model and discovered higher level of caveolin-1 (950 pg/ml) in tumor bearing animals treated with radiation, as compared to xenograft with radiosensitive lung cancer cells (450 pg/ml). Thus, we conclude that caveolin-1 is involved in radio-resistance and contributes to tumor aggression, and it has potential to be used as prognostic biomarker for radiation treatment response, and tumor progression for precision medicine in lung cancer patients.

Cytopathology fellowship recruitment: Has the time come to consider a unified approach?

INTRODUCTION: Cytopathology (CYP) fellowship training is a critical component of maintaining a skilled group of cytopathologists. For years, the recruitment process for CYP fellowship programs has remained unchanged, with individual programs outlining their own requirements and timeline, and applicants bearing the cost of travel and dealing with the variable processes outlined by individual programs. However, there has been renewed interest in analyzing the recruitment process for CYP fellowships to look for areas of potential improvement and uniformity. METHODS: With the goal of gauging the interest of CYP fellowship program directors (PDs) in a more unified approach to recruitment or a formal match process, the ASC Cytopathology Program Directors Committee (CPDC) surveyed PDs via SurveyMonkey and organized special webinars with polling over a 4-year time frame (2017-2021), and examined Qualtrics survey data collected by the American Board of Pathology (ABPath) in 2020. RESULTS: The response rate for PDs was greatest in a formal survey by the ABPath (66 respondents; 71% of PDs) conducted in 2020, and lower for an ASC survey in 2021 (61 respondents, 66% of PDs) and 2017 (19 respondents; 21% of PDs) and two recent ASC webinars (10 and 26 respondents; 11% and 28% of PDs). Support for a fellowship match process varied from 29% to 77%, respondent uncertainty ranged from 13% to 50%, and a lack of support ranged from 10% to 60%. In aggregate, approximately 56% of respondents would be in favor of a more standardized process. Recently, after hearing about other fellowships experimenting with a standardized process, the interest in a unified approach doubled from approximately 29% to 60%, and the percentage of PDs with uncertainty decreased from 50% to 26%. In the most recent follow up survey, interest reached the highest level of 77% among PDs. CONCLUSIONS: Herein we present several years of feedback from the CYP fellowship PD community regarding a more standardized approach to CYP fellowship recruitment, culminating in the latest survey with 77% of CYP fellowship PDs expressing interest. Thus, details about what a unified timeframe may look like for CYP fellowships is presented to show how this may improve the recruitment process for the mutual benefit for programs and applicants.

Pathologist Concordance for Ovarian Carcinoma Subtype Classification and Identification of Relevant Histologic Features Using Microscope and Whole Slide Imaging.

CONTEXT.­: Despite several studies focusing on the validation of whole slide imaging (WSI) across organ systems or subspecialties, the use of WSI for specific primary diagnosis tasks has been underexamined. OBJECTIVE.­: To assess pathologist performance for the histologic subtyping of individual sections of ovarian carcinomas using a light microscope and WSI. DESIGN.­: A panel of 3 experienced gynecologic pathologists provided reference subtype diagnoses for 212 histologic sections from 109 ovarian carcinomas based on optical microscopy review. Two additional attending pathologists provided diagnoses and also identified the presence of a set of 8 histologic features important for ovarian tumor subtyping. Two experienced gynecologic pathologists and 2 fellows reviewed the corresponding WSI images for subtype classification and feature identification. RESULTS.­: Across pathologists specialized in gynecologic pathology, concordance with the reference diagnosis for the 5 major ovarian carcinoma subtypes was significantly higher for a pathologist reading on a microscope than each of 2 pathologists reading on WSI. Differences were primarily due to more frequent classification of mucinous carcinomas as endometrioid with WSI. Pathologists had generally low agreement in identifying histologic features important to ovarian tumor subtype classification with either an optical microscopy or WSI. This result suggests the need for refined histologic criteria for identifying such features. Interobserver agreement was particularly low for identifying intracytoplasmic mucin with WSI. Inconsistencies in evaluating nuclear atypia and mitoses with WSI were also observed. CONCLUSIONS.­: Further research is needed to specify the reasons for these diagnostic challenges and to inform users and manufacturers of WSI technology.

RhoA/ROCK pathway inhibitor ameliorates erectile dysfunction induced by radiation therapy in rats.

OBJECTIVES: Prostate cancer (PCa) treatment with radiation therapy (RT) has an excellent cure rate. However, Radiation-induced Erectile Dysfunction (RiED) is a common and irreversible toxicity impacting quality of life, and there is no FDA approved specific drug for RiED. We previously showed that prostate RT increased RhoA/ROCK signaling in the cavernous nerve (CN) and penile tissues, which may lead to RiED in rats. In this study, we investigated whether RhoA/ROCK pathway inhibition by a specific inhibitor called Hydroxyfasudil (HF) can improve RiED in our well-established rat model. MATERIALS/METHODS: Male Sprague-Dawley rats were randomized to the following groups: sham-RT, HF-only, RT-only, and RT + HF. Rats were either exposed to a single dose of 25 Gy prostate-confined RT or a sham procedure. 10 mg/kg HF or normal saline was injected intraperitoneally. Erectile function was evaluated by intracavernosal pressure (ICP) and mean arterial pressure (MAP) measurements at week 14 post-RT. Cavernous nerve (CN) injury was evaluated by transmission electron microscopy (TEM), and penile tissue fibrosis by Masson trichrome staining (MT). RESULTS: We have found that the HF treatment prior to RT showed significant (p < 0.001) improvement in ICP/MAP ratio, area under the curve, and maximum ICP value, compared to RT-alone rats. Furthermore, RT + HF treated rats exhibited increased CN myelination and decreased axonal atrophy, comparted to RT-only. HF treatment showed significantly decreased penile tissue fibrosis (p < 0.05) compared to RT-alone treated rats. CONCLUSION: Our results provide the first preclinical evidence that targeting RhoA/ROCK pathway by HF may provide a novel therapeutic option for the treatment of RiED.

The Current State of Communication of Urgent and Significant, Unexpected Diagnoses in Anatomic Pathology.

CONTEXT.­: The concept of critical diagnoses in anatomic pathology is relatively recent and rigorous study of the issue is quite limited. The College of American Pathologists and Association of Directors of Anatomic and Surgical Pathology issued a consensus statement in 2012. There has been no multi-institutional study of communication policies since then. OBJECTIVE.­: To survey the policies of anatomic pathology laboratories regarding communication of critical values. DESIGN.­: A survey of the Association of Directors of Anatomic and Surgical Pathology membership was performed using a 14-question electronic survey tool. RESULTS.­: Responses were received from 38 institutions. Thirty-five of 38 (92%) had a policy on anatomic pathology critical values. Twenty-five of 38 (66%) respondents had read the College of American Pathologists/Association of Directors of Anatomic and Surgical Pathology consensus statement. Twelve of 38 (32%) institutions divided critical values into 2 categories, of which 9 used the College of American Pathologists/Association of Directors of Anatomic and Surgical Pathology terminology; 24 used only a single term, of which 11 used critical value. There was substantial variation in the diagnoses that were considered critical. A direct phone call to the responsible provider was uniformly considered an acceptable means of communication; all other methods had mixed or low support. The most common time frame was same day; many laboratories did not specify a timeframe. Most laboratories document date, time, and person to whom the result was communicated in the final report or an addendum report. Eighteen of 38 (47%) laboratories report an auditing mechanism for communication. CONCLUSIONS.­: Policies for communication of critical/urgent/significant, unexpected results in anatomic pathology are the norm. However, there remains significant variation between institutions in the details of these policies.

The Differential Diagnosis of Reparative Changes and Malignancy: Performance in the College of American Pathologists Pap Education and Proficiency Testing Programs.

CONTEXT.­: Repair is a challenging diagnosis and a significant source of false-positive (FP) interpretations in cervical cytology. No large-scale study of performance of repair in the liquid-based era has been performed. OBJECTIVE.­: To evaluate the performance of repair in the College of American Pathologists Pap Education and Proficiency Testing (PT) programs. DESIGN.­: The FP rate for slides classified as repair was evaluated by preparation type, participant type (cytotechnologist, pathologist, or laboratory), and program. The specific misdiagnosis category and individual slide performance were also evaluated. The rate of misclassification of slides as repair by participants for other diagnostic categories in the Pap Education program was assessed. RESULTS.­: The overall FP rate was 1700 of 12 715 (13.4%). There was no significant difference by program or preparation type. Within the Education program there was no difference by participant type, but pathologists' FP rate in the PT program (47 of 514, 9.1%) was significantly better than cytotechnologists in the PT program (51 of 380, 13.4%) and pathologists in the Education program (690 of 4900, 14.1%). High-grade squamous intraepithelial lesions/cancers (HSIL+) accounted for 1380 of 1602 FP interpretations (86%) in Education, but 43 of 98 (43.9%) in PT. Most slides had a low rate of misclassification, but a small number were poor performers. False-negative diagnosis of HSIL+ as repair was less common, ranging from 0.7% to 1.8%. CONCLUSIONS.­: Despite initial indications that liquid-based cytology might reduce the rate of misclassification of repair, FP interpretations remain common and are no different by preparation type. Misclassification is most commonly as HSIL or carcinoma, potentially resulting in significant patient harm.

Malignant Sex Cord-Stromal Tumor, Not Otherwise Specified, Harboring FOXL2, p53, and TERT Promoter Mutations: Report of a Case.

Rare sex cord-stromal tumors of the ovary cannot be further subclassified and are therefore designated "sex cord-stromal tumor-not otherwise specified." These tumors have highly varied morphology, and the literature describing them is limited. Herein, we report the pathology and clinical course of a 46-yr-old woman diagnosed with sex cord-stromal tumor-not otherwise specified. The tumor was composed predominantly of juvenile granulosa cell tumor histology, with elements of thecoma, adult granulosa, Sertoli, as well as poorly differentiated epithelioid and sarcomatoid components. Next-generation sequencing revealed a FOXL2 C134W mutation, seen most commonly in adult granulosa cell tumors, as well as mutations in TP53 (V172F) and TERT promoter (-124C>T). The patient exhibited an aggressive clinical course involving rapid recurrence with distant metastases that responded to 4 cycles of cisplatin, bleomycin, and etoposide.

EP4 and Class III ß-Tubulin Expression in Uterine Smooth Muscle Tumors: Implications for Prognosis and Treatment.

The microtubule-stabilizing agent docetaxel in combination with gemcitabine represents one of the most effective regimens against the aggressive gynecologic tumor leiomyosarcoma (LMS). Upregulation of class III ß-tubulin has previously been shown to confer taxane resistance in a variety of human cancers. Prostaglandin E2 receptor EP4 is linked to progression of a variety of human cancers and may represent a novel target for tumor inhibition in LMS. We evaluated the hypotheses that EP4 and class III ß-tubulin have increased expression in LMS in comparison to normal myometrium or benign tumors and that expression of class III ß-tubulin correlates with resistance to taxanes and poor clinical outcome. Gene expression was examined using TCGA data and correlated with clinicopathologic outcome which demonstrated that class III ß-tubulin is more highly expressed in more aggressive sarcomas with EP4 being widely expressed in all subtypes of sarcoma. Immunohistochemistry for EP4 and class III ß-tubulin was performed on patients with LMS, leiomyomatosis/STUMP, leiomyoma, and normal myometrium. Expression of EP4 and class III ß-tubulin were characterized for cell lines SK-UT-1, SK-UT-1B, and PHM-41 and these cell lines were treated with docetaxel alone and in combination with EP4 inhibitors. In taxane-resistant cell lines that overexpress class III ß-tubulin and EP4, treatment with EP4 inhibitor resulted in at least 2-fold sensitization to docetaxel. Expression of class III ß-tubulin and EP4 in LMS may identify patients at risk of resistance to standard chemotherapies and candidates for augmentation of therapy through EP4 inhibition.

Self-collected Papanicolaou tests in the United States market: more questions than answers.

The United States Food and Drug Administration held a public hearing in January 2018 to consider how it should evaluate a self-collection device for cervical cytology. Although no such device has been approved for use in the US market, the implications for patients and cytologists could be both sweeping and complex. Herein, the existing literature basis for self-collected Papanicolaou testing is reviewed, and some questions raised by this testing are considered. Questions include: what would be the value to patients; how effective could self-collected Papanicolaou tests be; how might ordering and collection work; what are the unique pre-analytic, analytic, and post-analytic challenges of self-collected Papanicolaou testing; and what effect might self-collection have on cervical cancer rates?

Digital image-assisted quantitative nuclear analysis improves diagnostic accuracy of thyroid fine-needle aspiration cytology.

BACKGROUND: Thyroid fine-needle aspiration (FNA) plays a key role in triaging thyroid nodules. Yet many cases are assigned to indeterminate categories. The new category "noninvasive follicular thyroid neoplasm with papillary-like features" (NIFTP) complicates thyroid cytology. Digital image-derived nuclear measurements might objectively distinguish papillary thyroid carcinoma (PTC) from benign nodules and NIFTP. METHODS: All thyroid FNAs from 2012 to 2016 of atypia of undetermined significance (A; n = 8) and suspicious for malignancy (S; n = 2) with sufficient cellularity and surgical follow-up, all FNAs preceding NIFTP (n = 6), and a random sample of PTC (n = 9) and benign (n = 10) cytology were studied. A modified Giemsa-stained slide from each case was scanned using the Aperio imaging system, and long (dl ) and short (ds )-axis diameters were measured for 125 nuclei per case. Nuclear area and elongation were calculated. RESULTS: Nuclear area was larger in PTC (mean, 77.2 µm2 [range, 70.6-86.0 µm2 ]) than benign (mean, 43.3 µm2 [range 38.2-52.2 µm2 ]) (P < .001). Nuclear areas from indeterminate FNAs segregated according to final histology (A/S PTC mean 72.7 µm2 , A/S benign mean 53.7 µm2 ; P = 0.004), and were not significantly different from definitive FNAs of the same diagnosis. NIFTP nuclear area was smaller than PTC (mean, 54.8 µm2 [range, 46.7-66.1 µm2 ]; P < .001). Nuclear elongation showed similar results, but with greater group overlap. CONCLUSION: Nuclear area and elongation can be calculated using a commercial digital imager; both correlate with the final surgical pathology diagnosis of PTC versus benign, including NIFTP. Area provides greater resolution than elongation. This technique could be used to resolve indeterminate cytology in which PTC is considered.

Distinguishing non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) from classic and invasive follicular-variant papillary thyroid carcinomas based on cytologic features.

INTRODUCTION: An international panel recently recommended reclassification of non-invasive follicular variant of papillary thyroid carcinoma (PTC) to non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). NIFTPs have little or no risk of recurrence and can be treated with lobectomy alone. Preoperative distinction of NIFTP from PTC will help avoid overtreatment. MATERIALS AND METHODS: All thyroid tumors with a histologic diagnosis of PTC and preceding diagnostic cytology (n = 299) over a 5-year period were identified. Cases meeting criteria for NIFTP were reclassified as such. All NIFTP cases with available cytology (n = 6) and a similar number of randomly selected invasive follicular variant of papillary thyroid carcinoma (IFVPTC; n = 9) and classic PTC (cPTC, n = 11) were evaluated for 18 cytologic features. RESULTS: A total of 35 (12%) lesions were reclassified as NIFTP, 194 (65%) were cPTC, and 70 (23%) were IFVPTC. The NIFTPs had a preceding cytologic interpretation of benign (31%), atypia of undetermined significance (34%), follicular neoplasm (9%), suspicious for malignancy (12%), or malignant (14%). Cytologically, NIFTP was distinguished from cPTC by absence of any architectural features in all 6 cases, and by absence of pseudoinclusions (P < 0.001) and multinucleated giant cells (P = 0.027) in nearly all. Nuclear pseudoinclusions (P = 0.001), marginal micronucleoli (P = 0.018), irregular branching sheets (P = 0.025), and linear arrangement (P = 0.025) favored IFVPTC over NIFTP. CONCLUSIONS: NIFTPs were originally assigned to a variety of cytologic categories. There are several cytologic differences between NIFTP and cPTC or IFVPTC. Our findings support restricting the definitive diagnosis of PTC to cases with architectural features of PTC and/or intranuclear pseudoinclusions.

Low-Grade Squamous Intraepithelial Lesion or High-Grade Squamous Intraepithelial Lesion? Concordance Between the Interpretation of Low-Grade Squamous Intraepithelial Lesion and High-Grade Squamous Intraepithelial Lesion in Papanicolaou Tests: Results From the College of American Pathologists PAP Education Program.

CONTEXT.­: Obtaining diagnostic concordance for squamous intraepithelial lesions in cytology can be challenging. OBJECTIVE.­: To determine diagnostic concordance for biopsy-proven low-grade squamous intraepithelial lesion (LSIL) and high-grade squamous intraepithelial lesion (HSIL) Papanicolaou test slides in the College of American Pathologists PAP Education program. DESIGN.­: We analyzed 121 059 responses from 4251 LSIL and HSIL slides for the interval 2004 to 2013 using a nonlinear mixed-model fit for reference diagnosis, preparation type, and participant type. We evaluated interactions between the reference diagnosis and the other 2 factors in addition to a repeated-measures component to adjust for slide-specific performance. RESULTS.­: There was a statistically significant difference between misclassification of LSIL (2.4%; 1384 of 57 664) and HSIL (4.4%; 2762 of 63 395). There was no performance difference between pathologists and cytotechnologists for LSIL, but cytotechnologists had a significantly higher HSIL misclassification rate than pathologists (5.5%; 1437 of 27 534 versus 4.0%; 1032 of 25 630; P = .01), and both were more likely to misrepresent HSIL as LSIL ( P < .001) than the reverse. ThinPrep LSIL slides were more likely to be misclassified as HSIL (2.4%; 920 of 38 582) than SurePath LSIL slides (1.5%; 198 of 13 196), but conventional slides were the most likely to be misclassified in both categories (4.5%; 266 of 5886 for LSIL, and 6.5%; 573 of 8825 for HSIL). CONCLUSIONS.­: More participants undercalled HSIL as LSIL (false-negative) than overcalled LSIL as HSIL (false-positive) in the PAP Education program, with conventional slides more likely to be misclassified than ThinPrep or SurePath slides. Pathologists and cytotechnologists classify LSIL equally well, but cytotechnologists are significantly more likely to undercall HSIL as LSIL than are pathologists.

High-grade Endometrial Carcinomas: Morphologic and Immunohistochemical Features, Diagnostic Challenges and Recommendations.

This review of challenging diagnostic issues concerning high-grade endometrial carcinomas is derived from the authors' review of the literature followed by discussions at the Endometrial Cancer Workshop sponsored by the International Society of Gynecological Pathologists in 2016. Recommendations presented are evidence-based, insofar as this is possible, given that the levels of evidence are weak or moderate due to small sample sizes and nonuniform diagnostic criteria used in many studies. High-grade endometrioid carcinomas include FIGO grade 3 endometrioid carcinomas, serous carcinomas, clear cell carcinomas, undifferentiated carcinomas, and carcinosarcomas. FIGO grade 3 endometrioid carcinoma is diagnosed when an endometrioid carcinoma exhibits >50% solid architecture (excluding squamous areas), or when an architecturally FIGO grade 2 endometrioid carcinoma exhibits marked cytologic atypia, provided that a glandular variant of serous carcinoma has been excluded. The most useful immunohistochemical studies to make the distinction between these 2 histotypes are p53, p16, DNA mismatch repair proteins, PTEN, and ARID1A. Endometrial clear cell carcinomas must display prototypical architectural and cytologic features for diagnosis. Immunohistochemical stains, including, Napsin A and p504s can be used as ancillary diagnostic tools; p53 expression is aberrant in a minority of clear cell carcinomas. Of note, clear cells are found in all types of high-grade endometrial carcinomas, leading to a tendency to overdiagnose clear cell carcinoma. Undifferentiated carcinoma (which when associated with a component of low-grade endometrioid carcinoma is termed "dedifferentiated carcinoma") is composed of sheets of monotonous, typically dyscohesive cells, which can have a rhabdoid appearance; they often exhibit limited expression of cytokeratins and epithelial membrane antigen, are usually negative for PAX8 and hormone receptors, lack membranous e-cadherin and commonly demonstrate loss of expression of DNA mismatch repair proteins and SWI-SNF chromatin remodeling proteins. Carcinosarcomas must show unequivocal morphologic evidence of malignant epithelial and mesenchymal differentiation.