ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 with a long-standing painless mass in the left lateral neck with rapid progression, pain, and skin ulceration — no other signifi- cant clinical burden. Computed tomography showed heterogene- ously enhancing mass in the left submandibular fossa, originating from the submandibular gland. Results: Grossly, a cream-colored, ulcerated, exophytic tumour of the skin, 3.4 x 2.8 cm in size and up to 2.6 cm in thickness, infiltrating the salivary gland parenchyma. Microscopically, the tumour consisted of three components: poorly differentiated squamous cell carcinoma (SCC), salivary duct carcinoma (SDC), and hyalinizing residual PA with no capsule. The SCC compo- nent infiltrated both the salivary gland and the skin without a visible pre-invasive component. SDC was visible in the salivary gland in SCC’s immediate vicinity. Immunohistochemically, the SCC cells expressed p40 and SDC expressed AR, mammaglobin, and GATA3. Targeted Next-Generation sequencing detected TTC23-PLAG1 fusion in carcinoma component. The patient was referred for radiotherapeutic treatment. Conclusion: The microscopic obser vation suppor ts the diagnosis of the carcinoma developed in PA with a rare, double mor phological differentiation (SCC and SDC). The detected PLAG1 fusion suppor ts t he diagnosis of doub l e d i f fe re n t i a t i on CXPA. Fu r t h e r re s e a rch mi gh t explore whether the histologic type of the CXPA malignant component modif ies t he sur vival and ef f icacy of t he implemented therapies. E-PS-11-018 Sinonasal glomangiopericytoma; a case report and histo- pathological overview H. Maddumage*, R. Rana, T. Wijesiri, S. Sunkaraneni, I. Bagwan *Royal Surrey County Hospital, United Kingdom Background & objectives: Approximately 75% of the sinonasal tumours are benign and squamous cell carcinoma is the most common malignant tumour. Sinonasal glomangiopericytoma (SNGP), account- ing for <0.5% of sinonasal neoplasms was first described in 1942 by Stout and Murray. Methods: Here, we present a clinico-pathological analysis of a nasal mass composed of pericytic cellular morphology. Results: A 78-year-old male presented with a mass in the left nasal cavity, which showed avid enhancement in MRI. Nasal polypectomy was performed. Histopathological examination revealed an ill-defined sub-epithelial tumour composed of sheets, lobules and nests of monotonous cells with round nuclei, indistinct nucleoli and scanty eosinophilic cytoplasm with minimal cytologic atypia in a background of collagenous stroma containing varying sized blood vessels showing dense perivascular hyalinization. There was no increased mitotic activity or necrosis. These lesional cells were positive for SMA, CD99, Factor XIIIa and Cyclin D1, supporting myoid differentiation typical of pericytes. The tumour showed diffuse dense nuclear expression of beta-catenin. Conclusion: Though the occurrence is rare, SNGP exhibits highly distinctive histopathologic features, as seen in this case. As the clinical behaviour of SNGP has been poorly understood, more cases need to be reported for better establishment of treatment modalities. Heterogenous mutations in the beta-catenin gene and expression of cyclin D1 have been identified in SNGP. E-PS-11-019 Submandibular adult type rhabdomyoma – a case report A. Alves*, R. Almeida, C. Courelas, J. Madeira, J. Gama, M.A. Cipriano *Centro Hospitalar e Universitário, Portugal Background & objectives: Rhabdomyoma is a benign skeletal muscle neoplasm, mainly cardiac. Extracardiac locations are rare. Morphologically, it is categorized as foetal, genital or adult types, depending on the degree of differentiation. Some cases are associ- ated with PTCH1 mutations and with Birt-Hogg-Dubé syndrome. Methods: We present a case of a 68-year-old male with a painless, submandibular mass, slowly growing for one year. The ultrasound study showed a well-defined mass consistent with the diagnosis of lipoma. He underwent surgical excision and the hypothesis of lipoma was doubted by the surgeon, due to the gross features. There was no relevant medical history. Results: Gross examination showed a well-circumscribed nodular lesion with 6,2x5,8x4,2cm, weighting 47g, with a yellowish, slightly lobulated outer surface, uniform elastic brown on cut surface. Histologically, it had expansile growth and was non-encapsulated, faintly lobulated. The cells were polygonal with abundant, eosinophilic and granular cytoplasm and the nuclei were round to oval, sometimes with prominent nucleoli. Some cells had vacuolated cytoplasm, resembling spider webs. Mitoses and necrosis were absent. Complementary immunohistochemical studies revealed diffuse positivity to desmin, and negativity to S-100 protein, CD68, TFE3 and myogenin. It was rendered a final diagnosis of adult type rhabdomyoma. Conclusion: Adult type rhabdomyoma is a benign neoplasm arising mainly in the head and neck region. Although rare, it is the commonest subtype of extracardiac locations and can be linked to a loss of function of the PTCH1 gene, which is, nevertheless, more frequent in the foetal type. There is a reported association to Birt-Hogg-Dubé syndrome. The main differential diagnosis are alveolar soft part sarcoma and granular cell tumour, the first one being a malignant entity with fusion gene involving TFE3. E-PS-11-020 Primary nasopharyngeal papillary adenocarcinoma: report of a rare entity and review of the literature S. Graja*, C. Chaari, I. Saguem, M. Manai, O. Boudawara, M. Mnejja, T. Boudawara, R. Kallel *Department of Pathology, Habib Bourguiba University Hospital, Sfax, Tunisia Background & objectives: Primary nasopharyngeal papillary adeno- carcinoma (PNPA) is a low-grade neoplasm with low propensity for recurrence and metastasis. Only few cases have been reported in the literature. We report here a new case of this rare entity to discuss its clinicopathological features. Methods: The histological features of PNPA occurring in a 25-year-old man who presented with unilateral nasal obstruction are described with a review of the related literature. Results: Nasal endoscopy showed a peduncle mass in the right nasal cavity. Cerebral scannography revealed an 18 mm tumour located in the upper wall of nasopharynx. Nasopharynx biopsy was performed. In microscopic examination, the tumour has a papillary architecture, with hyalinised fibrovascular cores lined by cuboidal to columnar cells with round vesicular nuclei presenting mild nuclear atypia. Some cells had nuclear groove. Nuclear pseudoinclusion and mito- sis were absent. There was neither necrosis nor psammoma body. Immunohistochemistry revealed that the tumour cells were positive for thyroid tissue factor-1 (TTF-1), keratin 7, keratin 19, epithelial S284