ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Background & objectives: Teratomas are germ cell tumours (GCT) containing cells from the three germ layers. The rise of somatic type malignancy in the context of GCT is rare phenomenon. Herein we describe a case, with 4 different somatic type malignancies. Methods: A 44-year-old male who presented with a complaint of persistent cough. Physical and systemic examination were unremarkable. A CT scan revealed a mediastinal mass. Fine needle aspiration results were suggestive of teratoma. The patient underwent surgical resection of the tumour. Results: Histopathologic examination revealed a mass measuring 20 x 13.5 x 11 cm surrounded by a thickened fibrotic capsule of variable thickness with areas of necrosis and cystic like appear- ance. Microscopically, the tumour was composed of heterologous components, mainly of mesenchymal but also of epithelial origin. Tumour demonstrated 4 different malignant components includ- ing: angiosarcoma (CD31+, CD34+, ERG+, Ki67 at 67%), chon- droblastic osteosarcoma, primordial cells tumour yolk sac type (PHOX2B+, GFAP+, NF+), well differentiated intestinal adeno- carcinoma (CK 8/18+, CK20+, and CDX20+). The rest of the tumour’s area consisted of mature hyaline cartilage, mature neural tissue with neural parenchyma (S100+, GFAP+), respiratory type epithelium with the presence of cilia and stratified squamous epithelium. Conclusion: The most frequent malignant component associated with GCT are sarcomas. In our case, the rise of 4 different somatic type malignancies is a rare finding, and to our knowledge, very few are reported so far. E-PS-23-002 Thymic carcinoma: a rare type of cancer. Clinicopathological study of 9 cases Y. Gómez Navarro*, M. Garcia Martos, C.M. Vieru, A. Panizo Santos *Hospital General Universitario, Spain Background & objectives: Thymic carcinomas are rare malignan- cies (less than 6/100,000 persons) from thymic epithelial cells in the anterior mediastinum. There are more than 10 subtypes. The presence of an isolated anterior mediastinal mass with no tumour elsewhere should make us suspect it. Methods: The pathology archives of two University Hospitals were searched for patients originally diagnosed as thymic carcinomas. The cases were reviewed by the authors (histopathology and immu- nophenotype). Clinical parameters such as age, gender, and follow up were obtained from the existing medical records. Results: Nine patients were identified: 4 males and 5 females, age ranged from 50 to 89 years (median 66,7 yrs.). The most common symptoms included chest pain and shortness of breath. CT scan showed in all patients large lesions in anterior mediastinum, meas- uring 2-10,5 cm and an advanced stage at diagnosis in three cases. Histologically the tumours were classified as squamous cell carcino- mas (6), neuroendocrine carcinoma (2) and high-grade undifferenti- ated carcinoma (1). Overall, 2 tumour was classified as moderately differentiated and 6 as poorly differentiated. Immunohistochemically, the tumours were positive for cytokeratin (100%), 4 for c-Kit, and 5 for CD5. None of the tumours showed staining for TTF-1 or napsin. Conclusion: Thymic carcinomas are a rare type of cancer that can show a variety of histologic types. Squamous cell carcinoma is the most frequent subtype in our series and accounts for 66,6%. Thymic Neuroendocrine carcinoma are exceedingly rare neo-plasms (only 2 cases in our series). Morphology and immunohistochemical mark- ers do not differentiate between carcinomas of different locations, thus making it difficult to establish the exact site of origin in cases of metastatic tumours. E-PS-23-003 Ectopic mediastinal parathyroid adenoma: report of unusual location and literature review O. Mnif*, R. Ayadi, E. Braham, M. Mlika, A. Rais, A. Ayadi, O. Ismail, F. El Mezni *Abderrahmen Mami Hospital, Tunisia Background & objectives: The mediastinal location of ectopic para- thyroid adenomasis is unusual and it reported in up to 10% of cases. It is an important cause of refractory and recurrent hyperparathyroidism. The aim: describe the clinicopathological characteristics and discuss the differential diagnosis of this entity. Methods: We performed a retrospective study of 14 cases of ectopic mediastinal parathyroid adenoma diagnosed at our depart- ment between 2004 and 2021. Results: There were 3 male and 11 female patients, aged between 15 and 71 years with a mean of 57,72 years. All patients presented with manifestations of chronic hypercalcemia. They checked ele- vated serum calcium levels and parathyroid hormone levels above normal range. Computed tomography of the chest showed an ante- rior mediastinal mass (n=10) or posterior mass (n=1). All patients underwent a surgical resection. The postoperative pathology test confirmed that the mass was diagnosed as a parathyroid adenoma. The patients had a successful postoperative recovery and then were discharged from the hospital in good condition. Serum calcium and parathyroid hormone levels were normalized immediately. Conclusion: An unusual location for a parathyroid adenoma is the mediastinum, and it can be a cause of persistent hyperparathy- roidism. This study helps bring to light the necessity to consider the diagnosis of an ectopic parathyroid adenoma as an important differential diagnosis in mediastinal tumour with persistent hyper- calcaemia, and as a cause of hyperparathyroidism. E-PS-23-004 Mesothlioma of the pericardium: report of 3 cases of a rare neoplasm S. Frini*, W. Majdoub, A. Baccouche, A. Bdioui, S. Mestiri, L. Jaidane, S. Hmissa *Pathology Department, Sahloul University Hospital of Sousse, Tunisia Background & objectives: Mesothelioma is a rare malignancy that develops from mesothelial cells lining the pleura, pericardium and peri- toneum. Pericardial mesotheliomas are exceedingly rare accounting for < 1% of malignant mesotheliomas .We describe the clinico-patholog- ical and immunohistochemical characteristics of primary pericardial mesothelioma (PPM). Methods: We report 3 cases of PPM collected from the Cancer Registry of the Center of Tunisia during a period of 22 years from 2000 to 2021. Results: Two patients were male, aged 56 and 65 years, pre- sented chronic pericarditis with recurrent pericardial effusion for, respectively, 3 and 4 months. The latter developed symptoms post COVID-19 infection. One female patient, aged 44 years, developed acute heart failure by pericardial tamponade . Clinico-radiological investigations suspected PPM in 2 cases. The 65-year-old patient underwent pericardial decortication while the others had pericar- dial biopsies. Microscopically, two mesotheliomas were of the epithelioid-subtype, displayed solid and tubulopapillary patterns, in which tumour cells showed mild nuclear atypia and low mitotic- rate. One case was of sarcomatoid-subtype , showed spindle cells with marked atypia and frequent mitotic figures. All tumours expressed Cytokeratin 5/6, Calretinin, Vimentine, and WT1. S348