Intraoperative Frozen Section Research Articles

Does the use of intraoperative frozen section of bone marrow from the cut end of the mandible help assess the adequacy of bone margins following mandibulectomy for oral cancer?

The adequacy of the cut end of the mandible following a segmental mandibulectomy done for oral cancer intraoperatively is at times assessed using a frozen section (FS)of the bone marrow (BM)at the cut ends. The study aimed to assess its utility to guide the intraoperative decision on the adequacy of bony margins. All patients with oral squamous cell carcinoma (OSCC)who underwent segmental mandibulectomy from January 2012 to December 2021 at our institute and for whom intraoperative FS of BM was utilized were included. We analyzed the sensitivity, specificity, and positive and negative predictive value (PPV,NPV) of this in predicting positive bone margins. A total of 457 patients were included in the study. The majority of the cases were per premium cases (n = 372, 81.4%). The median age of the cohort was 52 years (range: 22-80 years). Most patients had T4 disease (n = 406, 88.8%). On FS, BM was positive in only 18 patients (3.9%) for whom the bone margin was revised. BM biopsy report in the final histopathology was positive in 12 patients (2.2%). The sensitivity, specificity PPV, and NPV were 52.3%, 98.65%, 64.7%, and 97.7% respectively. No factors predicting BM positivity on FS could be identified in this cohort. The BM FS was positive in only a small percentage of patients, and it helped in reducing the bone margin positivity rate from 3.9% to 2.2% only. Hence the intraoperative BM FS seems to have limited utility as seen from our study.

Does perioperative hydrocortisone or indomethacin improve pancreatoduodenectomy outcomes? A triple arm, randomized placebo-controlled trial.

This trial evaluated whether anti-inflammatory agents hydrocortisone (H) and indomethacin (I) could reduce major complications after pancreatoduodenectomy (PD). Between June 2018 and June 2020, 105 patients undergoing PD with > 40% of acini on the intraoperative frozen section were randomized into three groups (35 patients per group): 1) intravenous H 100 mg 8 hourly, 2) rectal I suppository 100 mg 12 hourly, and 3) placebo (P) from postoperative day (POD) 0-2. Participants, investigators, and outcome assessors were blinded. The primary outcome was major complications (Clavien-Dindo grades 3-5). Secondary outcomes were overall complications (Clavien-Dindo grades 1-5), Clinically relevant postoperative pancreatic fistula (CR-POPF), delayed gastric emptying (DGE), postpancreatectomy hemorrhage (PPH), surgical site infections (SSI), length of stay, POD-3 serum amylase, readmission rate, and mortality. Major complications were comparable (8.6%, 5.7%, and 8.6% in groups H, I, and P, respectively). However, overall complications were significantly lower in group H than in group P (45.7% vs. 80.0%, p = 0.006). CR-POPF (14.3% vs. 25.7%, p = 0.371), PPH (8.6% vs. 14.3%, p = 0.710), DGE (8.6% vs. 22.9%, p = 0.188), and SSI (14.3% vs. 25.7%, p = 0.371) were comparable between groups H and P. Major complications and overall complications in group I were 5.7% and 60.0%, respectively, which were comparable to those in groups P and H. CR-POPF rates in groups H, I, and P were 14.3%, 17.1%, and 25.7%, respectively, which was comparable. H and I did not decrease major complications in PD.

Nationwide analysis of the breast cancer guidelines adherence in Bulgaria

IntroductionThe diagnosis and treatment of breast cancer have tremendously changed in the last decades improving the survival and quality of life of the patients. Adherence to clinical practice guidelines in oncology significantly improves patients’ recurrence-free and overall survival. Nowadays, no national registry/database for breast cancer patients is available. This study aims to perform a nationwide analysis of the breast cancer guidelines adherence in Bulgaria, in particular regarding the diagnostic methods for histological confirmation and the types of radical surgery performed using an artificial intelligence (AI) powered software. Materials and methodsWe analyzed data from January 2019 to August 2023 nationwide using the platform with access to anonymized medical information from Bulgaria's leading territorial oncology hospitals. A total of 13,790 patients met the inclusion criteria. ResultsThe gold standard diagnostic tool, CNB, was done in 5427 patients (39.35%), an intraoperative frozen section was performed as a method for confirmation of breast cancer in 6257 patients (45.37%) and the standard technique for lymph node evaluation, sentinel lymph node biopsy, was done in 357 patients (2.99%). ConclusionIn Bulgaria, there are still difficulties in achieving comparable rates of core-needle biopsy for the diagnosis of breast cancer and we have demonstrated unacceptably high rates of frozen section use for intraoperative diagnosis of breast cancer. Breast-conserving surgery is widely accepted and available, but still, the rates are lower than usual for developed countries. The rates of sentinel lymph node biopsy, however, are unreasonably low.

Hyalinizing clear cell carcinoma of the left main bronchus diagnosed with Ewing sarcoma breakpoint region 1::activating transcription factor 1 fusion: A case report

Rationale: Hyalinizing clear cell carcinoma (HCCC) of the bronchus is extremely rare. In addition, its rarity makes an accurate histological diagnosis difficult. Herein, we report a case of HCCC in the left main bronchus diagnosed by the detection of Ewing sarcoma breakpoint region 1::activating transcription factor 1 (EWSR1::ATF1) fusion transcript using reverse transcription-polymerase chain reaction (RT-PCR). Patient concerns: A 56-year-old woman presented with a tumor obstructing the left main bronchus on physical examination computed tomography. A bronchoscopic biopsy confirmed a malignant tumor but did not provide a definitive diagnosis. Interventions: Sleeve resection of the left main bronchus was performed. The intraoperative frozen section was negative for cancer in both the proximal and distal bronchial stumps. Diagnosis: General immunohistochemical staining was performed, and mucoepidermoid carcinoma and HCCC were suspected. RT-PCR revealed positive results for EWSR1::ATF1 fusion transcript, and the tumor was finally diagnosed as HCCC. Outcomes: The patient was discharged without any postoperative complications. Sixty-five months have passed since surgery, and no cancer recurrence has been observed. Lessons: Although hematoxylin and eosin staining and immunostaining alone were not sufficient to distinguish HCCC from mucoepidermoid carcinoma and other malignant tumors, adding genetic testing for EWSR1 rearrangement led to a definitive pathological diagnosis.

Intraoperative frozen section of subareolar tissue in nipple-sparing mastectomy: Towards a less is more approach

BackgroundNipple preservation contributes to aesthetic outcome and quality of life in women undergoing Skin-Sparing Mastectomy (SSM) with immediate breast reconstruction for the treatment of breast cancer. Intraoperative Frozen Section (IFS) has been advocated to facilitate conversion from Nipple-Sparing Mastectomy (NSM) to SSM in cases with positive subareolar margins. This study investigated the application of IFS at our comprehensive cancer centre. MethodsIn this single-centre retrospective study, for all patients who underwent therapeutic NSM with IFS from 2000 to 2021 pathological reports, patient- and tumour characteristics were retrieved. ResultsIn total 640 women were included in whom 662 intended NSMs with IFS had been performed. Sensitivity and specificity of frozen section compared with definitive histopathology were 75.2% and 98.5% respectively. In six women with a false positive result, the nipple had been removed. In 16 out of 32 women with a false negative result, the nipple was excised in a second procedure. In total 115 nipples were resected. In 40% of these nipples, no residual disease was detected. DiscussionIFS is a moderately sensitive and highly specific diagnostic tool to detect positive subareolar margins. An alternative approach is to omit frozen section but take intraoperative biopsies of the sub areolar margin, which are postoperatively analysed with definitive formalin-fixed paraffin-embedded histopathology. This allows for shared decision making regarding nipple excision in cases where minimal disease is found in subareolar tissue or cases with an indication for post-mastectomy radiotherapy.

Intraoperative Resection Guidance and Rapid Pathological Diagnosis of Osteosarcoma using B7H3 Targeted Probe under NIR-II Fluorescence Imaging.

Complete removal of all tumor tissue with a wide surgical margin is essential for the treatment of osteosarcoma (OS). However, it's difficult, sometimes impossible, to achieve due to the invisible small satellite lesions and blurry tumor boundaries. Besides, intraoperative frozen-section analysis of resection margins of OS is often restricted by the hard tissues around OS, which makes it impossible to know whether a negative margin is achieved. Any unresected small tumor residuals will lead to local recurrence and worse prognosis. Herein, based on the high expression of B7H3 in OS, a targeted probe B7H3-IRDye800CW is synthesized by conjugating anti-B7H3 antibody and IRDye800CW. B7H3-IRDye800CW can accurately label OS areas after intravenous administration, thereby helping surgeons identify and resect residual OS lesions (<2mm) and lung metastatic lesions. The tumor-background ratio reaches 4.42± 1.77 at day 3. After incubating fresh human OS specimen with B7H3-IRDye800CW, it can specifically label the OS area and even the microinvasion area (confirmed by hematoxylin-eosin [HE] staining). The probe labeled area is consistent with the tumor area shown by magnetic resonance imaging and complete HE staining of the specimen. In summary, B7H3-IRDye800CW has translational potential in intraoperative resection guidance and rapid pathological diagnosis of OS.

Optimizing Ideal Thickness of Sections for Epidermis in Intra-Operative Frozen Sections.

To estimate and evaluate the optimal thickness of tissue section for skin and dermal appendages intra-operatively and to compare the morphology and architecture of the epidermis and its appendages at 7 and 10 microns. After obtaining clearance from the institutional human ethical committee, 101 skin margins were prospectively analyzed using a two-step embedding technique. After multiple trials and errors, 7- and 10-micron thicknesses were selected for the present study. Artefacts, staining characteristics, cellular morphology, cellular outline, and nuclear outline were assessed and scored as unacceptable or acceptable. The data were entered in a Microsoft Excel spreadsheet and analyzed using SPSS software. There was a statistically significant difference between the sections obtained at 7 microns and 10 microns (p-value: <0.001), the latter were better in all the parameters analyzed. However, no difference was noted in the characteristics of the dermal appendages (p-value: >0.05). While mucosal margins can be obtained at the usual 5-7 microns, the same thickness is not optimal for skin margins intra-operatively. Frozen sections for the skin margins may be set at 10 microns, to save time, minimize artefacts, and for better readability.

166 (PB-073) Poster - Can we omit intraoperative frozen-section biopsy during breast-conserving surgery in selected patients?

166 (PB-073) Poster - Can we omit intraoperative frozen-section biopsy during breast-conserving surgery in selected patients?

Case report of high-grade pleomorphic sarcoma (rhabdomyosarcoma): a missed diagnosis in the non-healing post-traumatic wound of the elderly

Rhabdomyosarcoma (RMS) is known to be common childhood soft tissue sarcoma (STS). RMS is infrequent in adults. STS constitute &lt;1% of all adult solid malignant sarcomas and RMS accounts for 3% of all STS. The tumor is divided into three main subtypes-embryonal, alveolar, and pleomorphic (most common in adults). The most common primary sites are extremities. It’s an aggressive lesion with a high rate of metastasis. The patient presented with a non-healing wound over a posterior-medial aspect of the right leg with features suggestive of cellulitis. The patient gave a history of fall 5 months ago for which he took treatment at a local doctor, he continued to have severe pain for which an orthopedic opinion was taken and advised conservative management for an un-displaced fracture of the fibula. He later developed swelling over the lower-middle part of his right leg 3 months ago for which an ultrasound was done suggestive of a large amount of fluid suspicious of hematoma secondary to A-V malformation, an attempt for drainage of fluid was made leading to an evacuation of blood clots further procedure was abandoned and the patient transferred to our center. CT-angio demonstrated it as a heterogeneously attenuating solid cystic lesion. After appropriate consents-wound exploration was done with the evacuation of soft gelatinous material with pus discharge and blood clots. HPE-suggestive of high-grade pleomorphic rhabdomyosarcoma. The patient was advised amputation but denied any further treatment. Post-operative recovery was uneventful with no recurrence for the first 6 months after which the patient did not follow up. Post-traumatic mass at extremities should be evaluated with a high index of suspicion of STS. In case of doubt, either a preoperative biopsy or an intraoperative frozen section is a safe practice.

Latest Progress in Risk-Adapted Surgery for Medullary Thyroid Cancer.

(1) Background: The wider adoption of a preoperative ultrasound and calcitonin screening complemented by an intraoperative frozen section has increased the number of patients with occult sporadic medullary thyroid cancer (MTC). These advances offer new opportunities to reduce the extent of the initial operations, minimizing operative morbidity and the risk of postoperative thyroxin supplementation without compromising the cure. (2) Methods: This systematic review of the international literature published in the English language provides a comprehensive update on the latest progress made in the risk-adapted surgery for sporadic and hereditary MTC guided by an intraoperative frozen section. (3) Results: The current evidence confirms the viability of a hemithyroidectomy for desmoplasia-negative sporadic MTC. To add an extra safety margin, the hemithyroidectomy may be complemented by a diagnostic ipsilateral central node dissection. Despite the limited extent of the surgery, all the patients with desmoplasia-negative sporadic tumors achieved a biochemical cure with excellent clinical outcomes. A hemithyroidectomy decreases the need for postoperative thyroxine substitution, but a total thyroidectomy may be required for bilateral nodular thyroid disease. Hereditary MTC is a different issue. Because each residual thyroid C cell carries its own risk of malignant progression, a total thyroidectomy remains mandatory for hereditary MTC. (4) Conclusion: In experienced hands, a hemithyroidectomy, which minimizes morbidity without compromising the cure, is an adequate therapy for desmoplasia-negative sporadic MTC.

Neurovascular Structure-Adjacent Frozen-Section Examination (NeuroSAFE) Technique of Nerve-Sparing Robot-Assisted Radical Prostatectomy (RARP) in Indian Scenario: Technique, Feasibility, and Early Outcomes.

Potency and urinary continence are adversely affected post-prostatectomy. The primary objective is oncological safety by ensuring negative surgical margins (NSM) and best functional recovery through nerve preservation in appropriate patients. NeuroSAFE technique of intra-operative frozen-section (IFS) analysis was devised for comprehensive assessment of surgical margins adjacent to the neurovascular tissue surface of the prostate. We analyzed our initial experience with this technique. Five NS-RARPs were performed utilizing the NeuroSAFE technique between October 2021 and February 2022. Patient demographics, disease stage, operative console time, post-operative complications, final histopathology, biochemical recurrence (BCR), erectile function, and urinary continence were recorded. The mean age of patients was 59.2 ± 1.3years. All had clinically organ-confined disease with ISUP grade ≤ 3. The mean operative time of NS-RARP with NeuroSAFE was 240 ± 21min and average NeuroSAFE time was 45 ± 3.8min. All patients had NSM on IFS. No patient had Clavien-Dindo grade > 1 complications. Margins were negative on final histopathology. No patient had BCR at 6 and 12weeks. Three patients were able to have sexual intercourse and only one patient required single precaution pad at 12weeks. NeuroSAFE is feasible and can ensure intra-operative oncological safety of the NS procedure. Moreover, it gives the opportunity to convert positive surgical margin to prognostically favorable NSM by secondary resection. Our initial experience which is the first in India is encouraging with favorable functional outcomes. Large prospective studies and longer follow-up are required specially to evaluate the oncological benefit.

Diagnostic Utility of Fine-Needle Aspiration Cytology (FNAC) and Frozen Section Against Histopathology in Evaluating Benign and Malignant Breast Lesions.

Breastlesions, particularlylumps, pose concerns for females, varying between benign and malignant conditions. Accurate differentiation solely through clinical assessment is challenging, necessitating a definitive diagnostic strategy. Fine-needle aspiration cytology (FNAC) is integral in the "triple approach" to breast evaluation, offering simplicity, reliability, and cost-effectiveness. However, FNAC has limitations, occasionally failing to yield definitive diagnoses due to inherent constraints. Contrarily, frozen-section analysis, a long-standing intraoperative diagnostic method, plays a crucial role in swift diagnosis during surgeries. Despite technological advancements, frozen sections serve specific diagnostic purposes, confirming carcinoma when FNAC is inconclusive and evaluating resected margins. However, freezing artifacts may affect tissue assessment, emphasizing the continued reliance on histopathology for guiding treatment decisions. This study was conducted at KVG Medical College and Hospital, Sullia, Karnataka, India. It aimed to analyze the morphological characteristics of benign and malignant breast lesions using FNAC, frozen section, and histopathology and evaluate the sensitivity, specificity, and predictive values of FNAC and frozen section against histopathology as the reference standard. Across-sectional investigationwas carried out at a tertiary care hospital's Department of Pathology, on 60 female patients who presented with palpable breast masses over a span of two and a half years. FNACwas conducted, and the observations were classified into five categories as per the International Academy of Cytology guidelines. In addition, intraoperative frozen-section analysis was undertaken. A comparative analysis was conducted between the FNAC and intraoperative frozen-section findings, juxtaposed with the subsequent histopathological diagnoses. FNAC revealed 51.7% malignant, 45% benign, and 3.3% inadequate cases; the frozen-section analysis indicated 51.6% malignant, 45% benign, and 3.3% deferred cases; histopathology showed 53.3% malignant, 45% benign, and 1.6% borderline cases. FNAC demonstrated 93.9% sensitivity, 100% specificity, 100% positive predictive value (PPV), 93.1% negative predictive value (NPV), and 96.7% accuracy. The frozen-section analysis exhibited 96.9% sensitivity, 100% specificity, 100% PPV, 96.4% NPV, and 98.3% accuracy. Intraoperative frozen-section analysis displays superior diagnostic utility compared to preoperative FNAC. However, histopathology remains the definitive gold standard. Integrating all three diagnostic modalities is crucial for precise diagnosis and effective patientmanagement.

Role of Intraoperative Frozen Section Assessment of Proximal Bile Duct Margins and the Impact of Additional Re-Resection in Perihilar Cholangiocarcinomas.

Intraoperative frozen section (FS) analysis to assess the bile duct margin status is commonly used to assess the completeness of resection during surgery for perihilar cholangiocarcinoma (pCCA) resection. However, the impact of additional re-section on the long-term outcome after obtaining an initial positive margin remains unclear. Patients diagnosed as pCCA on preoperative imaging and subjected to curative intent surgery from May 2013 to June 2021 with a minimum follow-up of 2years were included. Intraoperative FS analysis of the proximal bile duct margin was performed in all patients. A positive margin was defined by the presence of invasive cancer. Out of the 62 patients with a preoperative diagnosis of pCCA on imaging, 35 patients were included for final analyses after excluding patients with inoperable disease (on staging laparoscopy or local exploration) and other/benign pathology on the final histopathology report. Out of the 35 patients, patients with postoperative 90-day mortality were excluded from the final survival analysis. FS analysis revealed an initial positive margin in 10 (28.5%) patients. Among 10 patients who underwent re-resection to achieve negative proximal margins, only 5 patients achieved a negative margin (secondary R0). An initial positive margin was associated with poor long-term outcomes. Median disease-free survival (DFS) and overall survival (OS) were 16 and 19.6months for patients with an initial positive margin, but 36 and 58.2months for patients with an initial negative margin, respectively (p = 0.012). The median DFS and OS were significantly lower for those with secondary R0 as compared to primary R0 (16 vs. 36months for DFS, p = 0.117 and 19.6 vs. 58.2months for OS, p = 0.027, respectively). An intraoperative FS positive proximal hepatic duct margin dictates poor long-term outcomes for patients with resectable pCCA. Additional resection has a questionable benefit on survival, when a secondary negative margin is achieved.

Development and validation of a predictive model for assessing the risk of follicular carcinoma in thyroid nodules identified as suspicious by intraoperative frozen section.

Follicular thyroid carcinoma (FTC) is the second most common thyroid malignancy and is characterized by a higher risk of distant metastasis compared to papillary thyroid cancer. Intraoperative frozen section (IOFS) diagnosis of FTC is challenging due to its limited sensitivity and accuracy, leading to uncertainty in intraoperative surgical decision-making. In response, we developed a predictive model to assess the risk of follicular carcinoma in thyroid nodules identified as suspicious for follicular neoplasm by IOFS. This model was derived from preoperative clinical and ultrasound data of 493 patients who underwent thyroid surgery at Ningbo Medical Center Lihuili Hospital. It identified five significant predictors of follicular carcinoma: nodule size, thyroglobulin (Tg) level, hypoechogenicity, lobulated or irregular margins, and thick halo. The model demonstrated robust discrimination and calibration, with an area under the curve (AUC) of 0.83 (95% CI: 0.77-0.90) in the training set and 0.78 (95% CI: 0.68-0.88) in the validation set. In addition, it achieved a sensitivity of 81.63% (95% CI: 69.39-91.84) and 68.00% (95% CI: 48.00--4.00), a specificity of 77.42% (95% CI: 72.18-82.66) and 72.51% (95% CI: 65.50-78.96), an accuracy of 78.1% (95% CI: 73.4-82.4) and 71.9% (95% CI: 65.3-78.6), a positive predictive value (PPV) of 41. 67% (95% CI: 35.65-48.84) and 26.79% (95% CI: 19.40-34.33), respectively, and a negative predictive value (NPV) of 95.61% (95% CI: 92.86-97.99) and 94.07% (95% CI: 90.44-97.08) in the training and validation sets, respectively. The model can accurately rule out FTC in low-risk nodules, thereby providing surgeons with a practical tool to determine the necessary extent of surgical intervention for nodules flagged as suspicious by IOFS.

Should we rely on frozen section during the reimplantation stage of revision knee arthroplasty?

To compare Frozen Section (FS) results during the reimplantation stage of revision knee arthroplasty, in patients without clinical signs of infection but with preoperative inconclusive serum inflammatory markers. Sections were revisited the day after surgery. Intraoperative FS (iFS) was accepted as positive when the presence of >5 polymorphonuclear neutrophils (PMNLs) in 5 separate high-power fields was determined according to the consensus criteria of the International Consensus on Musculoskeletal Infection. The clinical outcomes, cultures and diagnostic values of iFS and review FS (rFS) were analyzed. No complications developed after reimplantation in 66 (84.6%) of the 78 evaluated patients. Complications developed in 12 patients, six of whom were treated with re-explantation, four with arthrodesis and two with above-the-knee amputation. Both iFS and rFS yielded insignificant sensitivity and specificity (25% and 45.5%, 25% and 45%, respectively). There was no statistically significant difference between definitive culture and iFS and rFS. iFS evaluation is insufficient to exclude recovery from periprosthetic joint infection (PJI). Diagnosis of recurrence of infection in patients with indefinite serum inflammatory markers between the explantation and reimplantation interval remains challenging due to massive fibrosis that makes proper tissue sampling difficult. The attending physician should closely monitor clinical findings.

Intraoperative Frozen Section Analysis and an Audit of its Diagnostic Accuracy: A Cross-sectional Study from Maharashtra, India

Introduction: Frozen Section (FS) is a diagnostic technique performed intraoperatively to obtain relevant information about the primary diagnosis, margin status, or sentinel lymph nodes, which helps guide the course of surgery. With the prevalent use of FS, it is imperative to recognise and scrutinise its diagnostic pitfalls and make efforts for rectification. Aim: To compare diagnostic results obtained on FS with final paraffin-embedded histopathology and calculate the Diagnostic Accuracy (DA) of FS. Materials and Methods: This cross-sectional study was conducted in the Department of Pathology at a tertiary care hospital, DVVPFs Medical College in Ahmednagar district, Maharashtra, India over a period of two years from January 1, 2020, to December 31, 2021. The diagnosis provided on specimens received for intraoperative FS was compared with the final histopathological diagnosis, considered as the gold standard for the same specimen. The results were categorised as concordant, discordant, and deferred cases. The diagnosis on FS and the final histopathological diagnosis, along with relevant clinical data, were entered into an excel sheet. Further, the DA of FS was calculated. All the discordant cases were analysed. Statistical analysis utilised simple percentage calculations from the excel sheet. Results: A total of 130 cases were analysed using FS, with the most common indication being sentinel lymph node analysis to detect metastatic deposits in 72 (55.4%) cases. Out of the total 130 cases, 119 (91.5%) were concordant, 10 (7.7%) were discordant, and 1 (0.8%) was deferred due to an insufficient specimen. Therefore, the overall DA rate was found to be 91.5% with an error rate of 8.5%. Upon analysis of the 10 discordant cases, the cause of inaccuracy was technical error in 7 (70%) cases and interpretation error in 3 (30%) cases. Conclusion: The DA obtained in the present study was somewhat lower than expected due to technical errors during FS sectioning, leading to artifacts, especially during lymph node processing. Analysis of the discordant cases unveiled this deficit. Therefore, such assessment studies should be performed periodically as they assist in highlighting the shortfalls and provide a plan to boost DA.

Intraoperative frozen section for determining the extent of surgery in papillary thyroid carcinoma: comprehensive risk factor assessment.

There is much debate on the optimal treatment approach of papillary thyroid carcinoma (PTC). Different guidelines base recommendations on various risk factors. While diagnosing the various risk factors is difficult due to the technical limitations, intraoperative frozen section (IFS) may be a feasible method. We aim to real-time evaluate the multiple risk factors, including lymph node metastasis (LNM), extrathyroidal extension (ETE), multifocality using IFS, and then identify a more effective surgical plan, which may help avoid the need for a second surgery and improve prognosis of patients. We retrospectively reviewed the medical records of 364 patients from January 1, 2021 to December 31, 2021. All the patients were initially recommended to undergo a hemithyroidectomy (HT) with isthmusectomy and ipsilateral central compartment neck dissection (CCND). IFS would be executed immediately. Further total thyroidectomies (TTs) would be performed if: (I) results of IFS showed >5 LNM, or (II) there are 1≤ LNM ≤5 but with ETE and/or multifocal carcinoma. The patients were divided and investigated according to the extent of surgery. Based on the results of IFS, 72 patients underwent TT. The TT group displayed larger average tumor diameter, greater age, higher average body mass index (BMI), and elevated incidence of hypertension and hyperlipidemia compared to the HT group. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of IFS were 77.61%, 100%, 100%, and 88.46%, respectively. IFS is a highly reliable procedure. Comprehensively evaluating central compartment LNM, ETE, and multifocal carcinoma through IFS helps identify a more reasonable surgical option under the current clinical consensus, which may thus help avoid the need for a second surgery.

INTRAOPERATIVE FROZEN SECTION ANALYSIS OF ENDOMETRIOID OVARIAN BORDERLINE TUMOR: A DIFFICULT DIAGNOSIS

Abstract Introduction/Objective Borderline ovarian tumors (BOT) comprise approximately 15% of all primary ovarian neoplasms; of these endometroid borderline ovarian tumors (EBOT) are much rarer (2-3%). BOT is often potentially misdiagnosed as a malignant tumor based on its challenging histomorphological features and thus, treated aggressively. Herein, we present an unusual case of EBOT with adenofibromatous pattern in a 50-year-old gravida 3, para 2 female diagnosed on intraoperative frozen sections (IOFS). Methods/Case Report Patient with history of endometriosis presented with left lower quadrant abdominal pain. MRI revealed complex bilateral ovarian masses with solid and cystic components measuring 5 cm and 6.7 cm in right and left ovary, respectively. An ovarian malignancy was suspected. Patient underwent exploratory laparotomy, total abdominal hysterectomy with bilateral salpingo-opherectomy, and omentectomy. Grossly, bilateral ovaries (BO) showed intact capsule with solid and cystic components. On IOFS, the solid areas demonstrated endometrioid glands arranged in a lobular fashion with squamous morules. The cystic component demonstrated papillary projections with squamous differentiation. Cytology is mildly atypical at best. Based on these findings, a diagnosis of EBOT was made, necessitating staging. Differential diagnoses include atypical endometriosis, endometrioid adenofibroma (EAF) and endometrioid adenocarcinoma (EA). Lack of endometrial stroma surrounding the glands ruled out endometriosis. Presence of CC with papillary architecture ruled out EAF and lack of destructive stromal invasion with desmoplasia, confluence of glands and significant cytologic atypia ruled out EA. Final histopathological diagnosis of formalin-fixed paraffin-embedded specimen revealed EBOT, pT1bN0M0. Uterus and cervix revealed endometrial hyperplasia with atypia, adenomyosis, leiomyomas, and endocervical polyp. Results (if a Case Study enter NA) NA Conclusion The accurate diagnosis of BOT during IOFS is critical as it directs surgeons towards staging studies and in choosing conservative surgical treatment over aggressive treatment especially in cases of young women who desire future childbearing. As this is a rare entity, it serves the pathologist well to keep all relevant differential diagnoses in mind.

IMMU-25. ANALYSIS OF IMMUNOSUPPRESSIVE MYELOID CELLS IN THE GLIOBLASTOMA TUMOR MICROENVIRONMENT REVEALS THERAPEUTICALLY TARGETABLE IMMUNOMODULATORY SIGNALS ACROSS POPULATIONS

Abstract Immunosuppression in glioblastoma (GBM) remains a critical and poorly understood barrier to the development of effective novel therapies. Increasing evidence points to the critical role of immunosuppressive myeloid cells in the immunosuppressive tumor microenvironment and an intriguing target for ameliorating tumor-mediated immune suppression. Efforts to characterize the myeloid milieu in the tumor microenvironment have revealed a highly heterogenous population of cells with the capacity to exert immunosuppressive effects. In order to maximize the efficacy of potential therapeutic targets, we sought to identify immune checkpoint markers expressed across a range of immunomodulatory myeloid cell populations in the tumor microenvironment of patients undergoing resection for GBM. Freshly collected ultrasonic aspirate obtained during the primary surgery for GBM resection (based on preoperative imaging and intraoperative frozen section, later confirmed on final pathology) was prepared for high dimensional flow cytometry to quantify the immune checkpoint marker expression profile of a number of described immunosuppressive myeloid cell populations, including both monocytic and granulocytic myeloid-derived suppressor cells (mMDSC and gMDSC), and CD16+ non-classical monocytes (NCM). mMDSCs expressed particularly high levels of TIGIT (53.9±19.27%), which was also highly expressed in the NCM population (25.03±5.44%). NCMs also demonstrated high levels of B7H3 expression (39.85±18.05%), which has recently been implicated as an important immune checkpoint protein in GBM. gMDSCs demonstrated a rather different expression profile, with significantly higher levels of VISTA expression than other immunomodulatory markers (p&amp;lt; 0.05). These findings underscore the diversity of immunomodulatory signaling in the tumor-associated myeloid cell compartment, emphasizing the challenges in developing single-target immune checkpoint inhibitor therapy in GBM. Nevertheless, this data points to some common patterns of expression across major immunomodulatory cell populations that remain understudied in GBM and could herald more promising avenues of immunotherapy development.

Utility and diagnostic accuracy of intraoperative frozen sections in hepato-pancreato-biliary surgical pathology.

Hepato-pancreato-biliary (HPB) surgeries are one of the most challenging and complex procedures. Intraoperative frozen section (IFS) diagnosis plays a pivotal role in management decisions. Comprehensive large cohort studies evaluating utility of IFS in HPB malignancies are lacking. This study aimed to evaluate the accuracy of frozen section analysis and to analyse discrepancies and impact of IFS on the surgical decisions. This was a retrospective study of IFS received for the HPB specimens between years 2009 and 2021. The results were compared to the permanent sections to evaluate diagnostic accuracy, sensitivity and specificity. Indications, disagreements and impact on the surgical management were analysed. A total of 1008 specimens were evaluated: bile duct margin (279; 27.7%), gallbladder (203; 20.1%), liver lesions (125 cases; 12.4%), lymph nodes (147; 14.6%), pancreatic margin (120; 11.9%) and deposits (134; 13.3%). IFS were diagnosed as negative for malignancy (805; 79.9%), positive for dysplasia (8; 0.8%), suspicious for malignancy (6; 0.6%) and positive for malignancy (189; 18.8%). The overall diagnostic accuracy was 98.4%, and the discordant rate was 1.6%. The sensitivity, specificity, positive predictive value and negative predictive value were 94.7%, 99.4%, 97.5% and 98.6% respectively. The most important reason of discordant results was technical, followed by interpretational and sampling errors. The study demonstrates high diagnostic accuracy (98.4%) of IFS in a large dataset of HPB specimens. This comprehensive analysis apprises of the indications, errors and the impact of IFS diagnosis on subsequent HPB surgical management.