ECP 2023 Abstracts

S286 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 The results show that for all tested thresholds, the limit of consideration of the technique, set at 72% by protocol statistical methodology, was not only achieved but exceeded. Conclusion: A standardized method has been built to quantify and measure the distribution of the fluorescence signal in an entire surgical specimen. The quantification analysis strategy includes: the creation of a quantification tiles matrix, the normalization of the intensity values in the tumour and non-tumour zones, and the integration of detection thresholds to extract fluorescence signals from tumour areas. The sur- geon’s choice to privilege the sensitivity or specificity will guide the selection of the fluorescence threshold for the MAGNOLIA project. E-PS-12-014 Precursor lesions of odontogenic carcinomas: case report of an intraosseous mucoepidermoid carcinoma developed on a dentiger- ous cyst J. Castro*, J. Azevedo, M. Alzamora, A. Varelas, J. Costa, C. Meireles, T. Bacelar, M. Jácome *IPO-Porto, Portugal Background & objectives: Odontogenic carcinomas are rare neo- plasms but comprise a wide variety of different entities. Although these tumours are known to be related to the dental lamina, they are often diagnosed in advanced stages when precursor lesions are not evident. Methods: We present a case report of a 74-year-old man with intraosseous mucoepidermoid carcinoma associated with an odontogenic cyst. Imaging, histological and molecular studies were consistent with the diagnosis. In this case, there was evidence of malignant transformation of a denti- gerous cyst, suggesting a primary origin. We reviewed the current litera- ture about these possible precursor lessions of odontogenic carcinomas. Results: The patient was referred due to a 6.8 cm, solid and multi- loculated mass, centred in the body and left ramus of the mandible, involving an unerupted third molar. Histology showed a low-grade mucoepidermoid carcinoma, with areas of clear cells, developed on a dentigerous cyst. FISH analysis detected CRTC3-MAML2 fusion transcript, excluding primary intraosseous squamous cell carcinoma and clear cell odontogenic carcinoma. These tumours and others, such as ameloblastic carcinoma and ghost cell odontogenic carcinoma, can originate from the epithelium of odon- togenic cysts or the primitive rests of the dental lamina. Mucoepider- moid carcinoma may also have its origin in ectopic salivary gland tissue or the lining of the maxillary sinus. Conclusion: Precursor lesions of odontogenic carcinomas are scarcely described in the literature and even less documented with images. This case provides histological evidence of an intraosseous mucoepidermoid carcinoma arising from a dentigerous cyst. This finding suggests that other odontogenic carcinomas may share the same origin. However, developmental odontogenic cysts have their own distinct histogenesis. The dental lamina and ectomesenchyma may also play a role in the development of such lesions. E-PS-12-016 Sinonasal meningioma: a case report D. Ceyran*, T. Çiftçi, K. Başak *Kartal Dr. Lütfi Kırdar Hospital, Turkey Background & objectives: Extracranial meningiomas are quite rare in the sinonasal region. Four different mechanisms have been proposed for the development of extracranial meningiomas. One of these mecha- nisms is the extension of an intracranial meningioma into the nasal cavity by causing bone resorption. Methods: A 62-year-old female patient presented to our hospital with a 3-month history of nasal discharge. The patient had a history of surgery for olfactory groove meningioma 17 years ago, but the tumour could not be totally excised due to its location. A biopsy was recommended due to the presence of a mass in the right nasal cavity on physical examination. Results: Microscopically, a development characterized by oval- rounded, uniform-nucleus, wide, eosinophilic cytoplasm meningothe- lial cells forming a syncytial pattern starting from the nasal mucosa epithelium is observed. In a few foci, meningothelial cells form whirl- pool-like structures and a few psammoma-like microcalcifications are notable. Tumour cellularity is moderately elevated, and mitosis, necro- sis, and small cell components are not observed. Immunohistochemical examination revealed that the tumour cells were EMA, PR positive and Ki67 was seen in the most intense area at 5-6%. Based on these find- ings, the tumour lesion was evaluated as meningothelial meningioma, grade 1, and it was concluded that the previously existing olfactory groove meningioma had spread to the right nasal cavity. Conclusion: In the patient, the meningothelial meningioma in the right nasal cavity is a secondary lesion that developed due to the extension of the intracranial (olfactory groove) meningioma to the right nasal cavity 17 years ago. While meningiomas are generally benign tumours, the presence of optic nerve involvement, subtotal surgical resection, advanced age, and a Ki67 proliferation index of over 4% (5-6%) in our case can explain the clinically aggressive behaviour of the tumour despite its histomorphological Grade 1 status. E-PS-12-017 The possible prognostic role of Mena in oral squamous cell carcinoma R. Chiciudean*, L. Banias, Z. Kovacs, I. Jung, D. Bereczki-Temistocle, S. Gurzu *Department of Pathology, Clinical County Emergency Hospital of Târgu Mure ș , Romania Background & objectives: The prognostic role of HPV status in oral squamous cell carcinoma (OSCC) was hypothesized to be related to the actin cytoskeleton. This paper aimed to assess the possible connection between HPV status and Mena, an actin cytoskeleton remodelling marker. Methods: This retrospective cohort analysis was conducted on 43 patients diagnosed with OSCC at the Department of Pathology of the Clinical County Emergency Hospital of Târgu Mure ș , Romania. The HPV status was assessed through DNA-HPV testing. Mena expression was detected immunohistochemically, and the cytoplasm positivity was assessed in the tumour cells. Results: Of the 43 examined cases, 18 tumours were HPV positive and 16 of them were Mena positive, compared with only 14 of the 25 HPV-negative tumours (p<0.0001). Mena was not expressed in normal oral tissue, but its expression increased in parallel with tumour de- differentiation (p=0.03): 8 of the 13 well-differentiated SCCs expressed Mena; in the moderately differentiated category, 12 out of 16 were positive whereas in 10 of the 14 poorly differentiated SCCs the tumour cells were marked by the examined protein. Regarding localization, tumours of the tongue and lips exhibited higher Mena upregulation compared to the floor of the mouth and maxillary sinus (p<0.0001). Conclusion: In OSCC, Mena upregulation seems to increase with tumour de-differentiation and the presence of HPV mutations. Further studies are needed to further elucidate the role of the HPV mutation in relation to cytoskeleton modulation and the particularities in HPV-associated OSCC. Shaping molecular profiles of HPV-associated OSCC and establishing the role of the actin cytoskeleton can establish the basis for the development of new therapeutic tools for the personalized therapeutic approach. E-PS-12-018 A simple case of a Warthin tumour or maybe more? F. Dolkiras*, N. Stavrinou, E. Spiteri, E. Athanasiou, C. Vourlakou *Department of Pathology, Evangelismos General Hospital, Athens, Greece Background & objectives: A 76years old woman presented with a painless cervical mass measuring 3cm in greatest diameter. Biopsy of the mass was performed.