2025 Poster Presentations
P323: RE-CLASSIFICATION OF HISTORIC CASES OF SINONASAL UNDIFFERENTIATED CARCINOMA USING CONTEMPORARY DIAGNOSTIC UNDERSTANDING - A 24-YEAR EXPERIENCE
Blake M Lindsay, BSci, Adv, Hons, I, MD1; Peta-Lee Sacks, BMed, MD1; Jamie Brown, MD2; Minh Anh Nguyen, MD3; Ruta Gupta, MBBS, MD, FRCPA3; Peter Earls, MBBSHons, DipRACOG, FRACGP, FRCPA, FIA2; Larry Kalish, MBBS, Hons, I, MS, MMed, Clin, Epi, FRACS1; Richard Harvey, MD, PhD, FRACS1; Raewyn Campbell, FRACS, BMedHons, BAppScPhysio, GradDipE1; 1Rhinology and Skull Base Research Group, St Vincent's Centre for Applied Medical Research; 2SydPath, St Vincent's Hospital; 3Royal Prince Alfred Hospital, Sydney
Introduction: Sinonasal undifferentiated carcinoma (SNUC) is a rare and aggressive malignancy of the nasal and paranasal sinus epithelium, characterized by its rapid progression and poor prognosis. Due to its rarity, understanding the molecular and histopathological characteristics of SNUC remains challenging. Diagnosis of SNUC is effectively one of exclusion, if the features on pathology do not meet the diagnostic criteria of another sinonasal carcinoma. Modern understanding of newly described neoplasms (e.g. NUT midline carcinoma) and more recently understood subsets of SNUC (e.g. SMARCB1 deficient sinonasal carcinoma) would suggest that cases previously labelled as SNUC may in fact have an alternative diagnosis based on current pathology criteria.
Aim: This study re-evaluates historic tissue samples from patients diagnosed with SNUC in Sydney, Australia over a span of 24 years, utilising modern diagnostic criteria and methods. We aim to better understand SNUC by stratifying existing cases into contemporarily understood sinonasal carcinoma subsets or alternative newly described diagnoses to better understand patients’ clinical treatment options, response to treatment and overall prognosis.
Methods: Archival tumour tissue specimens of adult patients diagnosed with SNUC were collected (n = 23) from our institutions and were subjected to comprehensive histopathological re-review and immunohistochemical analysis. Additionally, molecular profiling using next-generation sequencing was performed in instances where the final diagnosis remained unclear. Pathology data were correlated with patients’ presentation, treatment course and clinical outcomes.
The re-evaluation of historic tissue samples not only enhances our understanding of SNUC but also highlights the importance of revisiting archived specimens using contemporary diagnostic tools.
Conclusion: This study underscores the value of retrospective analysis in rare cancers such as SNUC and related newly discovered differential diagnoses. Moving forward, continued efforts in collaborative research and data sharing will be essential to validate these findings and translate them into clinical practice, ultimately improving outcomes for patients with this challenging malignancy.