ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 melanoma metastasis in a parotid lymph node. The patient’s his- tory unveiled that he used to have a cutaneous pigmented lesion in the right supraorbital area which suffered a complete regression over time. Conclusion: A malignant melanoma metastasis should not be excluded, even in cases with an absent primary tumour site. A complete examination of the head and neck region and a detailed history of the patient can aid in discovering the primary tumour. Funding: This work was supported by a grant from the Romanian National Authority for Scientific Research, CNCS–UEFISCDI (project no. 20 PCCF/2018; code. PN-III-P4-ID-PCCF-2016-0006). E-PS-11-011 Viable adenosquamous carcinoma of the larynx after chemo- therapy and radiotherapy - a case report G. Stanc*, N. Novkovic, G. Galanopoulos, S. Laskaris, C. Vala- vanis, E. Souka *Pathology Department Metaxa Cancer Hospital, Greece Background & objectives: Adenosquamous carcinoma (ASC) of upper aerodigestive tract is a rare malignant tumour. Laryngeal ASC is extremely unusual malignant neoplasm, representing only 0.35%–0.5% of all laryngeal malignancies. Because of its rarity there is no overall consensus as to its best management. Methods: A female 67-year-old presented to our hospital for a laryngeal lesion in the glottic region. The biopsy showed moderate to high-grade invasive squamous carcinoma. She received neoadjuvant therapy (chemotherapy, radiotherapy). In the biopsy after neoadjuvant therapy the diagnosis of viable invasive squamous carcinoma remained. A total laryngectomy was performed. Results: On gross examination an ulcerated polypoid glottis tumour, 3cm. in diameter, with transglottis extension was recog- nized. In the same container we received two lymph nodes 0.2cm and 0.3cm. in great diameter. On histopathologic examination, a viable ulcerated high grade squamous cell carcinoma was revealed [CK5/6 (+), p40 (+), p16 (-)] admixed with adenocarcinoma, mod- erately differentiated [CK18/8 (+), EMA (+)]. The two lymph nodes were negative for metastasis. The patho- logical stage (in our specimen) was ypT3N0, with response after neoadjuvant therapy R2 (CAP 2021). Conclusion: ACS is a malignant neoplasm with an aggressive course, characterized by local recurrences, with early cervical lymph node metastasis and distant dissemination, most commonly in lung. The prognosis is poor and the mean overall survival rate is approximately 2-3 years. The current treatment involves surgical excision and/or adjuvant chemoradiotherapy, depending on the stage. E-PS-11-012 A GLI-full diagnosis – a case report of a GLI-1 re-arranged head and neck mesenchymal neoplasm H. Walsh*, S.A. Khurram, L. Hook *Unit of Oral and Maxillofacial Pathology, School of Clinical Den- tistry, University of Sheffield, United Kingdom Background & objectives: A 19-year-old male patient presented complaining of a 12-month history of a gradually increasing lump on his posterior dorsal tongue. The lesion was reported to have ruptured prior to excision. The lesion was excised and sent for histological assessment. Methods: Histological examination showed a well circumscribed, mul- tinodular, and submucosal tumour without a capsule. The tumour mass was formed by nests of monotonous cells separated by a fine vascular network. The cells had round to ovoid nuclei with clear to eosino- philic cytoplasm. Minimal atypia and mitoses were seen. Evidence of lymphovascular invasion was identified in the superficial vasculature. Results: Immunohistochemistry showed diffuse Vimentin expres- sion in lesional cells. Weak focal positivity was seen for CD56 and GLUT1, with SMA expression only at the periphery of the tumour islands. Staining for S100, SOX10, Desmin, CD31, CD34, AE1/AE3, HMB-45, CD99, ERG, CD68, EMA, Calcitonin and muscle specific actin was negative. Pan-RNA fusion panel testing confirmed the presence of an ACTB-GLI1 fusion protein leading to a definitive diagnosis of a GLI-1 re-arranged head and neck mesenchymal neoplasm. Conclusion: GLI 1 re-arranged mesenchymal neoplasms are a relatively newly described entity with a propensity to arise in the tongue within the head and neck regions. The distinct morpho- logical and variable immunohistochemical profile should raise the possibility of this entity as a differential diagnosis and prompt pathologists to undertake additional molecular testing to establish the presence of GLI1 re-arrangement. Emerging evidence suggests these lesions have the potential for malignant behaviour therefore knowledge of this entity is paramount for appropriate management. E-PS-11-013 Neuroendocrine large cell carcinoma with myoepithelial dif- ferentiation of the parotid gland - a case report G. Stanc*, N. Novkovic, M. Sevastiadou, E. Kostopoulos, S. Sta- sinopoulou, C. Valavanis, E. Souka *Pathology Department Metaxa Cancer Hospital, Greece Background & objectives: Salivary gland carcinoma is a rare neo- plasm accounting for 0.3% of all cancers. Large cell neuroendocrine carcinoma (LCNC) in the salivary glands is extremely rare, with poor prognosis similar to small cell carcinoma (SCC). Methods: A male 58-years-old was referred to our hospital for swelling on the right site of the parotid area. Imaging revealed a circumscribed solid mass 5.5cm in size. A fine needle aspiration was performed and the cytological features shows a high-grade carcinoma. Total parotidectomy was performed. Results: On macroscopic examination of the salivary gland, weigh- ing 39g. and 7.5X4.5X2.5cm in dimensions, a yellowish myxoid tumour was found. Microscopy showed a high grade neoplasm within myxoid stroma, with organoid infiltrative pattern, composed by large cells with marked nuclear atypia and hyperchromatic nuclei. Up to 10 mitotic figures / 10HPF, comedo necrosis and perineural infiltration were observed. The immunohistochemistry was positive for CK8/18, CK5/6, CK14, CD117, GFAP, S-100, Synaptophysin, Chromogranin A. Ki-67 was positive in 40-50%. Negative immunoreactivity was observed for CK7, EMA, TTF-1. PETscan demonstrated no lesions elsewhere. Based on morphological and immunophenotypic features the diag- nosis of a primary LCNC with myoepithelial differentiation of the parotid gland was confirmed. Conclusion: The lung is the most common site of this tumour, but LCNC has been found in other organs. The treatment for salivary gland carcinoma is mainly surgery, including primary tumour resec- tion with or without neck lymph node dissection and adjuvant ther- apy. LCNCs are very rare and there is no consensus on management guidelines. The main differential diagnosis of LCNC is with poorly differentiated carcinoma or squamous cell carcinoma. Immunohis- tochemistry is important in making the right diagnosis of LCNC. S282