The evolving landscape of salivary gland tumors.

Salivary gland cancers are a rare, histologically diverse group of tumors. They range from indolent to aggressive and can cause significant morbidity and mortality. Surgical resection remains the mainstay of treatment, but radiation and systemic therapy are also critical parts of the care paradigm. Given the rarity and heterogeneity of these cancers, they are best managed in a multidisciplinary program. In this review, the authors highlight standards of care as well as exciting new research for salivary gland cancers that will strive for better patient outcomes.

The histological spectrum and immunoprofile of head and neck NUT carcinoma: A multicentre series of 30 cases.

BACKGROUND AND AIM: Head and neck nuclear protein of testis carcinoma (HN-NUT) is a rare form of carcinoma diagnosed by NUT immunohistochemistry positivity and/or NUTM1 translocation. Although the prototype of HN-NUT is a primitive undifferentiated round cell tumour (URC) with immunopositivity for squamous markers, it is our observation that it may assume variant histology or immunoprofile. METHODS: We conducted a detailed clinicopathological review of a large retrospective cohort of 30 HN-NUT, aiming to expand its histological and immunohistochemical spectrum. RESULTS: The median age of patients with HN-NUT was 39 years (range = 17-86). It affected the sinonasal tract (43%), major salivary glands (20%), thyroid (13%), oral cavity (7%), larynx (7%), neck (7%) and nasopharynx (3%). Although most cases of HN-NUT (63%) contained a component of primitive URC tumour, 53% showed other histological features and 37% lacked a URC component altogether. Variant histological features included basaloid (33%), differentiated squamous/squamoid (37%), clear cell changes (13%), glandular differentiation (7%) and papillary architecture (10%), which could co-exist. While most HN-NUT were positive for keratins, p63 and p40, occasional cases (5-9%) were entirely negative. Immunopositivity for neuroendocrine markers and thyroid transcription factor-1 was observed in 33 and 36% of cases, respectively. The outcome of HN-NUT was dismal, with a 3-year disease specific survival of 38%. CONCLUSIONS: HN-NUT can affect individuals across a wide age range and arise from various head and neck sites. It exhibits a diverse spectrum of histological features and may be positive for neuroendocrine markers, potentially leading to underdiagnosis. A low threshold to perform NUT-specific tests is necessary to accurately diagnose HN-NUT.

Novel prognostic nomogram for predicting recurrence-free survival in medullary thyroid carcinoma.

AIMS: Recently, there have been attempts to improve prognostication and therefore better guide treatment for patients with medullary thyroid carcinoma (MTC). In 2022, the International MTC Grading System (IMTCGS) was developed and validated using a multi-institutional cohort of 327 patients. The aim of the current study was to build upon the findings of the IMTCGS to develop and validate a prognostic nomogram to predict recurrence-free survival (RFS) in MTC. METHODS AND RESULTS: Data from 300 patients with MTC from five centres across the USA, Europe, and Australia were used to develop a prognostic nomogram that included the following variables: age, sex, AJCC stage, tumour size, mitotic count, necrosis, Ki67 index, lymphovascular invasion, microscopic extrathyroidal extension, and margin status. A process of 10-fold cross-validation was used to optimize the model's performance. To assess discrimination and calibration, the area-under-the-curve (AUC) of a receiver operating characteristic (ROC) curve, concordance-index (C-index), and dissimilarity index (D-index) were calculated. Finally, the model was externally validated using a separate cohort of 87 MTC patients. The model demonstrated very strong performance, with an AUC of 0.94, a C-index of 0.876, and a D-index of 19.06. When applied to the external validation cohort, the model had an AUC of 0.9. CONCLUSIONS: Using well-established clinicopathological prognostic variables, we developed and externally validated a robust multivariate prediction model for RFS in patients with resected MTC. The model demonstrates excellent predictive capability and may help guide decisions on patient management. The nomogram is freely available online at https://nomograms.shinyapps.io/MTC_ML_DFS/.

Independent Validation of the International Grading System for Medullary Thyroid Carcinoma: A Single Institution Experience.

Medullary thyroid carcinoma (MTC), an uncommon C cell thyroid malignancy, accounts for a disproportionate number of thyroid cancer deaths. To predict MTC clinical behavior, the recent international MTC grading system (IMTCGS) was published combining features from the Memorial Sloan Kettering Cancer Center and Royal North Shore Hospital grading systems that incorporates mitotic count, necrosis, and Ki67 proliferative index (Ki67PI). The IMTCGS appears promising, but independent validation data are limited. Here, we applied the IMTCGS to our institutional MTC cohort and assessed its ability to predict clinical outcomes. Our cohort comprised 87 MTCs (30 germline and 57 sporadic). Slides for each case were reviewed by 2 pathologists and histologic features recorded. Ki67 immunostaining was performed on all cases. Each MTC was graded with the IMTCGS based on tumor necrosis, Ki67PI, and mitotic count. Cox regression analysis was performed to assess the impact of various clinical and pathological data on disease outcomes, including overall survival (OS), disease-free survival, disease-specific survival (DSS), and distant metastasis-free survival. In our MTC cohort, 18.4% (n = 16/87) were IMTCGS high grade. IMTCGS grade was strongly prognostic for OS, disease-free survival, DSS, and distant metastasis-free survival on univariate analysis and multivariable analysis in both the entire MTC cohort and in the sporadic subset. Among the individual IMTCGS parameters, while all 3 were associated with poorer survival outcomes on univariate analysis, necrosis had the strongest association with all survival parameters on multivariable analysis, whereas Ki67PI or mitotic count was associated only with OS and DSS. This retrospective study independently demonstrates that the IMTCGS is valid for grading MTCs. Our findings support incorporating IMTCGS into routine pathology practice. IMTCGS grading may help clinicians to better predict the prognosis of MTC. Future studies may shed light on how MTC grading should impact treatment protocols.

Ki67 proliferation index in medullary thyroid carcinoma: a comparative study of multiple counting methods and validation of image analysis and deep learning platforms.

AIMS: The International Medullary Thyroid Carcinoma Grading System, introduced in 2022, mandates evaluation of the Ki67 proliferation index to assign a histological grade for medullary thyroid carcinoma. However, manual counting remains a tedious and time-consuming task. METHODS AND RESULTS: We aimed to evaluate the performance of three other counting techniques for the Ki67 index, eyeballing by a trained experienced investigator, a machine learning-based deep learning algorithm (DeepLIIF) and an image analysis software with internal thresholding compared to the gold standard manual counting in a large cohort of 260 primarily resected medullary thyroid carcinoma. The Ki67 proliferation index generated by all three methods correlate near-perfectly with the manual Ki67 index, with kappa values ranging from 0.884 to 0.979 and interclass correlation coefficients ranging from 0.969 to 0.983. Discrepant Ki67 results were only observed in cases with borderline manual Ki67 readings, ranging from 3 to 7%. Medullary thyroid carcinomas with a high Ki67 index (≥ 5%) determined using any of the four methods were associated with significantly decreased disease-specific survival and distant metastasis-free survival. CONCLUSIONS: We herein validate a machine learning-based deep-learning platform and an image analysis software with internal thresholding to generate accurate automatic Ki67 proliferation indices in medullary thyroid carcinoma. Manual Ki67 count remains useful when facing a tumour with a borderline Ki67 proliferation index of 3-7%. In daily practice, validation of alternative evaluation methods for the Ki67 index in MTC is required prior to implementation.

The solid variant of papillary thyroid carcinoma: a multi-institutional retrospective study.

AIMS: The definition of papillary thyroid carcinoma, solid variant (PTC-SV) varies from >50% to 100% of solid/trabecular/insular growth (STI). We aimed to identify prognostic factors and to establish an appropriate STI cutoff for PTC-SV in this multi-institutional study of 156 PTCs with STI. RESULTS: Nodal metastases were seen in 18% and were associated with a higher percentage of papillary and STI. When substratified by infiltration/encapsulation status, the STI percentage did not impact the risk of nodal metastasis. pN1 stage was seen in 51% of infiltrative tumours and 1% of encapsulated lesions. Overall, PTC with STI had an excellent prognosis. The 10-year disease-free survival (DFS) was 87% in the entire cohort, 94% in encapsulated lesions, and 76% in infiltrative tumours. The STI percentage did not impact DFS. Fifty-four patients had noninvasive encapsulated lesions with 2-100% STI. None developed recurrence. Encapsulated lesions were enriched with RAS mutations (54%), whereas infiltrative lesions lacked RAS mutations (4%). The BRAF V600E mutation was an infrequent event, being seen in 11% of the entire cohort. CONCLUSION: In PTC with STI, the determining factor for nodal metastasis and DFS is the encapsulation/infiltration status rather than the STI percentage. Encapsulated noninvasive tumours with STI follow an indolent course with a very low risk of nodal metastasis and recurrence. Overall, PTC with STI has an excellent prognosis, with a 10-year disease-specific survival (DSS) and DFS of 96% and 87%, respectively. Therefore, the classification of SV-PTC as an aggressive PTC subtype may be reconsidered.

Secretory carcinoma of the salivary gland: a multi-institutional clinicopathologic study of 90 cases with emphasis on grading and prognostic factors.

Secretory carcinoma (SC) is a rare form of salivary carcinoma that was first described in 2010 and is characterized by ETV6::NTRK3 fusion in most cases. In this large retrospective study, we aimed to identify adverse clinicopathologic factors and propose a prognostically relevant grading scheme for SC. METHODS: A detailed clinicopathologic review was conducted on 90 SCs from the major and minor salivary glands. RESULTS: The median age at presentation was 50 years (range: 7-93). Sixty-nine (77%) tumours originated from major salivary glands, whereas the remaining 21 involved minor salivary glands.Six cases (7%) had cervical nodal metastasis. Only lymphovascular invasion (LVI) was associated with a risk of nodal metastasis (P < 0.05). The 5-year disease-specific survival and disease-free survival (DFS) were 98% and 87%, respectively. On univariate survival analysis, adverse prognostic factors associated with decreased DFS included minor salivary gland origin, atypical mitosis, high mitotic index, high-grade transformation (HGT), necrosis, nuclear pleomorphism, infiltrative tumour border, fibrosis at the invasive front, LVI, positive margin, and advanced pT stage (P < 0.05). When adjusted for pT stage and margin status, mitotic index, LVI, nuclear pleomorphism, and HGT remained as independent prognostic factors. CONCLUSION: We therefore propose a two-tiered grading system for SC. The low-grade SC is defined as those with <5 mitoses /10 high-power fields and no tumour necrosis, and high-grade SC as those with ≥5 mitoses /10 high-power fields and/or necrosis. This proposed grading system can be useful to risk stratify patients with SC for appropriate clinical management.

Direct regulation of GAS6/AXL signaling by HIF promotes renal metastasis through SRC and MET.

Dysregulation of the von Hippel-Lindau/hypoxia-inducible transcription factor (HIF) signaling pathway promotes clear cell renal cell carcinoma (ccRCC) progression and metastasis. The protein kinase GAS6/AXL signaling pathway has recently been implicated as an essential mediator of metastasis and receptor tyrosine kinase crosstalk in cancer. Here we establish a molecular link between HIF stabilization and induction of AXL receptor expression in metastatic ccRCC. We found that HIF-1 and HIF-2 directly activate the expression of AXL by binding to the hypoxia-response element in the AXL proximal promoter. Importantly, genetic and therapeutic inactivation of AXL signaling in metastatic ccRCC cells reversed the invasive and metastatic phenotype in vivo. Furthermore, we define a pathway by which GAS6/AXL signaling uses lateral activation of the met proto-oncogene (MET) through SRC proto-oncogene nonreceptor tyrosine kinase to maximize cellular invasion. Clinically, AXL expression in primary tumors of ccRCC patients correlates with aggressive tumor behavior and patient lethality. These findings provide an alternative model for SRC and MET activation by growth arrest-specific 6 in ccRCC and identify AXL as a therapeutic target driving the aggressive phenotype in renal clear cell carcinoma.

Emergency Department Placement and Management of Indwelling Urinary Catheters in Older Adults: Knowledge, Attitudes, and Practice.

UNLABELLED: Indwelling urinary catheters (IUCs) are placed frequently in older adults in the emergency department (ED). Though often a critical intervention, IUCs carry significant risks. Our objective was to examine current knowledge, attitudes, and practice of emergency nurses and other providers regarding IUC placement and management in older adults. METHODS: We surveyed ED providers at a large, urban, academic medical center. We developed questionnaires using items from previously validated instruments and questions created for this study. We also assessed providers' management of 25 unique clinical scenarios, each representing an established appropriate or inappropriate indication for IUC placement. RESULTS: 129 ED providers participated: 43 nurses and 86 other providers. Ninety-one percent of nurses and 87% of other providers reported comfort with appropriate indications for IUC placement. Despite this, on the clinical vignettes, nurses correctly identified the appropriate approach for IUC placement in only 40% of cases and other providers in only 37%. Practice varied widely between individual providers, with the nurse participants reporting appropriate practice in 16%-64% of clinical scenarios and other providers in 8%-68%. Few nurses or other providers reported reassessing their patients for IUC removal at transfer to the hospital (28% of nurses and 7% of other providers), admission (24% and 14%), or shift change (14% and 8%). DISCUSSION: Although emergency nurses and other providers report comfort with appropriate indications for IUC placement, reported practice patterns showed inconsistencies with established guidelines. Wide practice variation exists between individual providers. Moreover, nurses and other providers infrequently consider IUC removal after placement.

Grading medullary thyroid carcinoma on fine-needle aspiration cytology specimens with the International Medullary Thyroid Carcinoma Grading System: A cytologic-histologic correlation.

BACKGROUND: Medullary thyroid carcinoma (MTC) is a rare cancer of parafollicular C-cell origin. The International MTC Grading System (IMTCGS) incorporates mitotic activity, the presence of necrosis, and the Ki67 proliferation rate (PR) to classify MTCs as low or high grade. The ability to predict IMTCGS grade in cytology was assessed. METHODS: MTCs with cytology and subsequent surgical follow-up were reviewed. Cytology slides were reviewed for mitotic figures, apoptoses, and necrosis, and a Ki67 PR was calculated when possible. Findings were correlated with final IMTCGS grade. RESULTS: Twenty-five MTC fine-needle aspirations (FNAs) were identified, with nine identified as high grade (36%). By using a PR cutoff of 5%, Ki67 on FNA material (Ki67FNA) showed 92% concordance (n = 22 of 24) with surgical Ki67 and a correlation coefficient (R2) of 0.72. Sensitivity and specificity of Ki67FNA for predicting high-grade MTC were 38% and 100%, respectively. Multiple mitotic figures were present in a single slide of 43% (n = 3 of 7) of evaluable high-grade MTCs, whereas only one of 16 low-grade MTCs showed a single mitotic figure. Definitive apoptoses were present in five of seven high-grade MTC FNAs but were absent in 16 low-grade MTCs. The sensitivity and specificity of apoptoses/necrosis on cytology for high-grade MTCs were 71% and 88%, respectively. CONCLUSIONS: Ki67FNA ≥5% shows low sensitivity but high specificity for predicting high-grade MTC. The presence of multiple mitotic figures in a single slide or definitive apoptotic bodies are both highly suggestive of high-grade MTC, and should warrant a close examination for necrosis and a careful Ki67 PR count.

Salivary Mucinous Adenocarcinoma Masquerading as Chronic Submandibular Sialolithiasis.

A patient with chronic submandibular sialolithiasis underwent conservative treatment with appropriate imaging and multiple biopsies that continually revealed chronic inflammation. Due to continued symptoms, the patient underwent eventual excision and finaly pathology revealed salivary mucinous adenocarcinoma, which is a rare and poorly understood salivary malignancy. Persistent diagnostic workup and a high suspicion for salivary gland lesions is important for appropriate diagnosis and treatment. More attention and research on this specific entity can help future clinicians better diagnose and treat patients with a similar presentation. Laryngoscope, 134:2258-2261, 2024.

Monkeypox virus cytologic findings: An institutional experience with an emerging threat.

OBJECTIVES: Mpox is a viral disease caused by monkeypox, a highly contagious orthopoxvirus that resulted in a global outbreak beginning in spring 2022. Diagnosis is confirmed via polymerase chain reaction (PCR) testing of swabs from mucocutaneous lesions. Rare reports have documented the histologic changes of mpox lesions, but the cytologic features have not been described. We present the cytology findings of samples taken from swabs of mucocutaneous mpox lesions in 3 different patients. METHODS: The patients were all male, aged 55, 43, and 37 years, all with mpox confirmed by PCR testing. Swabs from chest (cases 1 and 2) and tongue (case 3) lesions were directly sampled and submitted in Aptima (case 1) or PreservCyt solution (cases 2 and 3). Liquid-based preps were prepared and stained using the Papanicolaou method. Specimens were assessed for viral cytopathic changes. RESULTS: All cases showed nuclear cytopathic changes (enlarged nuclei with open chromatin and prominent red nucleoli), 2 cases demonstrated multinucleated keratinocytes, and 1 case showed potential Guarnieri bodies. The chromatin margination and nuclear molding typical of herpesviruses was not appreciated. CONCLUSIONS: The cytopathic changes of monkeypox are not specific, but their recognition could prompt appropriate PCR testing. Monkeypox shows distinct cytologic changes compared with herpesviruses.

Atrophic changes in thyroid tumors are strong indicators of underlying DICER1 mutations: a bi-institutional genotype-phenotype correlation study.

Somatic and biallelic DICER1 mutations are reported in subsets of thyroid tumors, supporting the role of this gene in thyroid tumor development. As recent studies have brought attention to macrofollicular patterns, atrophic changes, and papillary structures as being associated with DICER1 mutations, we sought to explore these observations in a bi-institutional cohort. A total of 61 thyroid lesions (54 tumors and 7 cases of thyroid follicular nodular disease; TFND), including 26 DICER1 mutated and 35 DICER1 wildtype controls were subjected to histological re-investigation and clinical follow-up. DICER1-mutated lesions showed a statistically significant association with younger age at surgery (29.2 ± 12.5 versus 51.3 ± 18.8, p = 0.0001), a predominant macrofollicular growth pattern (20/26 mutated cases versus 18/35 wildtype; p = 0.01) and atrophic changes (20/26 mutated cases versus 2/35 wildtype; p = 0.0001). Similar results were obtained when excluding TFND cases. We also present clinical and histological triaging criteria for DICER1 sequencing of thyroid lesions, which led to the identification of DICER1 variants in 16 out of 26 cases (62%) when followed. Among these, 3 out of 12 cases with available data were found to carry a constitutional DICER1 mutation. This observation suggests that the majority of DICER1 mutations are somatic-however implies that sequencing of constitutional tissues could be clinically motivated. We conclude that DICER1 mutations are amassed in younger patients with macrofollicular-patterned tumors and, most strikingly, atrophic changes. Given the rate of constitutional involvement, our findings could be of clinical value, allowing the pathologist to triage cases for genetic testing based on histological findings.

Comprehensive evaluation of cytomorphologic, histologic, and molecular features of DICER1-altered thyroid lesions on FNA: A multipractice experience.

BACKGROUND: DICER1 mutations, though infrequent, are encountered on preoperative molecular testing of indeterminate adult and pediatric thyroid fine-needle aspiration (FNA) specimens. Yet, published cytomorphologic features of DICER1-altered thyroid lesions are limited. Cytomorphological features of DICER1-altered thyroid lesions were examined in a multipractice FNA cohort with clinical, radiological, and histologic data. METHODS: The cohort comprised 18 DICER1-altered thyroid FNAs, with 14 having slides available and eight having corresponding surgical resections. Smears, ThinPrep, and formalin-fixed cell block slides were reviewed and correlated with histology, when available. Clinical and radiologic data were obtained from the medical record. RESULTS: Most DICER1-altered FNAs were classified as atypia of undetermined significance (94.4%). DICER1 mutations occurred in codons 1709 (50%), 1810 (27.8%), and 1813 (22.2%). One patient had an additional DICER1 p.D1822N variant in both of their FNAs. Lesions were often hypoechoic (35.3%) and solid (47.1%) on ultrasound. Notable cytomorphologic features include mixed but prominent microfollicular or crowded component, variable colloid, and insignificant nuclear atypia. On resection (n = 10), histologic diagnoses ranged from benign follicular adenoma and low-risk follicular thyroid carcinoma to high-grade follicular-derived nonanaplastic thyroid carcinoma. Subcapsular infarct-type change was the most common histologic change. There was no evidence of recurrence or metastasis in eight patients on limited follow-up. CONCLUSION: DICER1-altered thyroid lesions occurred frequently in young females and FNAs show RAS-like cytomorphology including crowded, mixed macro-/microfollicular pattern, and bland nuclear features. On resection, DICER1-altered thyroid lesions include benign (50%), low-risk lesions (30%), or high-risk malignancies (20%).

Association of the Genomic Profile of Medullary Thyroid Carcinoma with Tumor Characteristics and Clinical Outcomes in an International Multicenter Study.

Purpose: The prognostic importance of RET and RAS mutations and their relationship to clinicopathologic parameters and outcomes in medullary thyroid carcinoma (MTC) need to be clarified. Experimental Design: A multicenter retrospective cohort study was performed utilizing data from 290 patients with MTC. The molecular profile was determined and associations were examined with clinicopathologic data and outcomes. Results: RET germ line mutations were detected in 40 patients (16.3%). Somatic RET and RAS mutations occurred in 135 (46.9%) and 57 (19.8%) patients, respectively. RETM918T was the most common somatic RET mutation (n = 75). RET somatic mutations were associated with male sex, larger tumor size, advanced American Joint Committee Cancer (AJCC) stage, vascular invasion, and high International Medullary Thyroid Carcinoma Grading System (IMTCGS) grade. When compared with other RET somatic mutations, RETM918T was associated with younger age, AJCC (eighth edition) IV, vascular invasion, extrathyroidal extension, and positive margins. RET somatic or germ line mutations were significantly associated with reduced distant metastasis-free survival on univariate analysis, but there were no significant independent associations on multivariable analysis, after adjusting for tumor grade and stage. There were no significant differences in outcomes between RET somatic and RET germ line mutations, or between RETM918T and other RET mutations. Other recurrent molecular alterations included TP53 (4.2%), ARID2 (2.9%), SETD2 (2.9%), KMT2A (2.9%), and KMT2C (2.9%). Among them, TP53 mutations were associated with decreased overall survival (OS) and disease-specific survival (DSS), independently of tumor grade and AJCC stage. Conclusions: RET somatic mutations were associated with high-grade, aggressive primary tumor characteristics, and decreased distant metastatic-free survival but this relationship was not significant after accounting for tumor grade and disease stage. RETM918T was associated with aggressive primary tumors but was not independently associated with clinical outcomes. TP53 mutation may represent an adverse molecular event associated with decreased OS and DSS in MTC, but its prognostic value needs to be confirmed in future studies.

Significance of oncocytic features in poorly differentiated thyroid carcinoma - a bi-institutional experience.

Poorly differentiated thyroid carcinoma (PDTC), defined by Turin criteria, comprises a subset of high-grade follicular-derived thyroid carcinomas with intermediate prognosis. While differentiated oncocytic thyroid carcinomas demonstrate clinicopathologic and genetic differences compared to their non-oncocytic counterparts, similar data is limited in oncocytic (Hurthle) PDTCs (OPDTCs). Here, we assessed the impact of various oncocytic cut-offs in PDTCs on clinical, histologic and survival parameters.Our bi-institutional cohort comprised 210 primary PDTCs with available slides reviewed by at least one pathologist. Histologic features, including oncocytic fraction, were recorded. Clinicopathologic data were obtained, including overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS), locoregional recurrence free survival (LRRFS), and distant metastasis-free survival (DMFS). Radioactive iodine avidity data was available for 125 PDTCs based on postoperative whole-body scanning.Within our cohort, 39.0% PDTCs had any oncocytic component with 24.8% meeting the 75% World Health Organization (WHO) oncocytic definition. Any oncocytic component and > 25% oncocytic cut-off correlated with decreased DSS and LRRFS, respectively, compared to non-oncocytic PDTCs (NOPDTCs) on univariate and multivariate analysis. The 100% oncocytic cut-off was significant for DSS on univariate analysis but a non-significant trend on multivariate analysis. Any oncocytic cut-off (100%, > 75%, > 50%, > 25%, or > 0%) conferred higher radioactive iodine (RAI)-refractoriness to OPDTCs compared to NOPDTCs. NF1 and PTEN alterations were enriched in OPDTCs (40% vs. 0%, and 60% vs 8%, respectively), whereas NRAS mutations were frequent in NOPDTCs (47% vs. 7%).Among PDTCs, the presence of oncocytes led to downward trend in all outcome parameters, especially for DSS and LRRFS. OPDTCs were enriched in NF1 and PTEN mutations. Consistently, all oncocytic cut-offs were associated with RAI-refractoriness. Accordingly, additional studies are needed to reassess the current 75% cut-off used to define oncocytic thyroid lesions.

Exploration of Digital Image Analysis for Ki67 Quantification in the Grading of Medullary Thyroid Carcinoma: A Pilot Study with 85 Cases.

BACKGROUND: Although uncommon, medullary thyroid carcinoma (MTC) accounts for a significant proportion of thyroid cancer deaths. Recent studies have validated the two-tier International Medullary Thyroid Carcinoma Grading System (IMTCGS) to predict clinical outcomes. A 5% Ki67 proliferative index (Ki67PI) cut-off separates low-grade from high-grade MTC. In this study, we compared digital image analysis (DIA) to manual counting (MC) for determining the Ki67PI in a MTC cohort, and explored the challenges encountered. METHODS: Available slides from 85 MTCs were reviewed by two pathologists. The Ki67PI was documented by immunohistochemistry for each case, scanned with the Aperio® slide scanner at 40× magnification, and quantified using the QuPath® DIA platform. The same hotspots were screenshot, printed in color, and blindly counted. For each case, over 500 MTC cells were counted. Each MTC was graded using IMTCGS criteria. RESULTS: In our MTC cohort (n = 85), 84.7 and 15.3% were low- and high-grade with the IMTCGS. In the entire cohort, QuPath® DIA performed well (R2 = 0.9891) but appeared to undercall compared to MC. QuPath® performed better in high-grade cases (R2 = 0.99) compared to low-grade cases (R2 = 0.7071). Overall, Ki67PI determined with either MC or DIA did not affect IMTCGS grade. Encountered DIA challenges include optimizing cell detection, overlapping nuclei, and tissue artifacts. Encountered MC challenges include background staining, morphologic overlap with normal elements, and counting time. CONCLUSION: Our study highlights the utility of DIA in quantifying Ki67PI for MTC and can serve as an adjunct for grading in conjunction with the other criteria of mitotic activity and necrosis.