ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Conclusion: As MLAs demonstrate varied architectural patterns, it often could lead to misdiagnosis, especially on a small biopsy specimen. Endometrial MLA represents a distinct subtype of endo- metrial carcinomas associated with KRAS-mutations and charac- teristic immunohistochemical findings. Clinically, MLAs show an aggressive behaviour with a substantial risk for lung metastasis. Frequent association with adenomyosis, no mesonephric remnant, and mutations in PIK3CA and ARID1A suggest a Müllerian origin of the endometrial MLAs. PS-08-026 HPV-positive status and p53 alterations are associated with improved disease-free survival in patients with vulvar squa- mous cell carcinoma A. Saco*, N. Carreras-Dieguez, C. Manzotti, M. del Pino, N. Rak- islova, I. Trias, I. Ribera-Cortada, S. Alos, R. López del Campo, S. Diaz-Mercedes, L. Marimon, M.T. Rodrigo, J. Ordi *Hospital Clínic Barcelona, Spain Background & objectives: Three clinically distinct subtypes of vulvar squamous cell carcinomas (VSCC) have been described on the basis of human papillomavirus (HPV) status and p53 altera- tions. HPV-positive and p53 wild-type status have been reported to confer better disease-free survival and overall survival. Methods: 193 surgically treated from 1975 to 2021 in a single institution in Spain were included. Median follow-up was 69 months (range 1–285). p53 was determined by immunohistochemistry (IHC) and HPV by p16 IHC. We assessed the survival of the patients stratified in three groups (HPV-positive, HPV-negative/ p53 mutant and HPV-negative/p53 wild-type). Correlations with outcome were analysed using Kaplan-Meier survival curves. Results: 35 patients (18.1%) had HPV-positive VSCC, 137 (70.9%) HPV-negative/p53 IHC abnormal and 21 (10.8%) HPV- negative/p53 wild-type carcinomas. Age at diagnosis of women with HPV-positive tumours was lower than those with HPV- negative/p53 abnormal and HPV-negative/p53 wild-type VSCC (median 62 years vs. 76 and 77 years, respectively, p=0.06). Patients with HPV-positive tumours showed lower rates of relapse than those with HPV-negative carcinomas (p<0.01). Remarkably, among women with HPV-negative VSCCs, patients with p53 abnormal IHC staining showed lower rates of relapse than those with p53 wild-type IHC (p=0.01). However, no differences in disease-specific survival or in FIGO stage (initial vs advanced) were identified among the three groups (p=0.40 and 0.37, respectively). Conclusion: Our findings indicate that patients with HPV-positive VSCC, as well as patients with HPV-negative carcinomas with p53 abnormal IHC staining show improved disease-free survival, but these factors seem not to influence disease-specific survival. Patients with HPV-negative carcinomas, particularly those with p53 wild-type neoplasms may warrant wider margins and more strict surveillance after surgery due to their high risk of relapse. PS-08-027 Intraoperative pathologic evaluation of the ovary: a 21-year institutional practice review T. André Sousa Oliveira*, M. Pinho, D. López-Presa *Department of Pathology - Hospital de Santa Maria, CHULN, Portugal Background & objectives: Intraoperative pathologic evaluation may assist in therapy management of ovary pathology by confirm- ing diagnosis and cancer type and providing information about the extent of the disease. Herein, we reviewed our institution’s practice regarding this examination. Methods: We analysed all reports of ovarian intraoperative pathol- ogy evaluations from a tertiary healthcare institution spanning a 21-year period [2001-2021], totalling 329 cases. Intra- and postop- erative diagnosis, gross pathology features, lesion size, bilateral- ity and number of frozen blocs analysed were recorded. Of these, only 254 had intra- and postoperative responses available and were selected as our study cohort. Results: Most patients were ≥45-years old (74.0%) and suspected of having an adnexal/ovarian neoplasm (n=205; 80.7%), an inde- terminate cystic lesion (n=24; 9.4%) or another infrequent rea- son (n=25; 10.4%); 14 patients (5.5%) underwent examination for bilateral lesions. Frozen sections were done in 75.2%, averaging 1.9 sections/exam, with the remainder being only evaluated mac- roscopically. A concordant intra- and postoperative result occurred in 239 cases (96.5%), with discordant results arising from: over- valuing malignant potential (n=2; 0.8%), tumour misclassification (n=2; 0.8%), misinterpretation of artefactual tissue as carcinoma (n=1; 0.4%) and inadequate sampling (n=1; 0.4%). Three cases were deferred (1.2%). As higher-grade components cannot be con- sistently excluded, intraoperative results undervaluing malignant potential were considered concordant. Conclusion: Ovarian intraoperative examination remains a reliable and useful tool for deciding therapeutic management. A systematic approach to grossing, sampling and clear communication between clinician and pathologist are encouraged to avoid misdiagnosis and wrongful treatment. When a precise diagnosis is not feasible, either the most probable diagnosis can be reported with an indication of other differential diagnosis which cannot be excluded, or the examination can be deferred when doubt remains after careful examination and consideration. PS-08-028 A new homologous recombination deficiency (HRD) test in ovarian cancer provides a high diagnostic yield J. Kim*, G.Y. Kwon, S. Baik, S. Lee, E. Oh, J. Hong, S. Kim, K. Lee *Department of Pathology, Kangnam Sacred Heart Hospital, Hal- lym University College of Medicine, Republic of Korea Background & objectives: Homologous recombination repair (HRR) pathway deficiency (HRD) is involved in the carcinogenesis of ovarian cancer (OC) and poly(ADP-ribose) polymerase (PARP) inhibitors can be effective for patients with HRD. We investigated the HRD status and its clinical significance in OC. Methods: We used a new HRD solution combining information from germline and somatic HRR mutations including BRCA1 and BRCA2 with a measure of genomic scarring. On next-generation sequencing in 39 OCs, BRCA mutations and amplification of associated genes were detected. Genomic integrity (GI) index was calculated and a GI status was concluded. By combining the results, HRD status was subsequently determined. Results: HRD status in 34 (87.2%) OCs was successfully ana- lysed. Five cases (12.8%) were undetermined due to inconclusive or rejected GI index. Twenty three (67.6%) out of 34 case were HRD positive and 11 (32.4%) cases were HRD negative. Tumours with BRCA1/2 mutation were 9 (26.5%) and tumours with posi- tive GI index were 21 (61.8%). HRD was associated with high- grade serous carcinoma and high FIGO stage (≥IIIB) (p=0.032 and 0.028, respectively). Patients with high GI index (>9.7) displayed better disease-free survival compared to those with low GI index (p=0.012). S113