ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 K.E. Akar*, E. Çeşmecioğlu Karavin, M. Say, H.K. Türköz *Marmara University Pendik Training and Research Hospital Department of Pathology, Istanbul, Turkey Background & objectives: Extraskeletal myxoid chondrosarcoma is a malignant mesenchymal tumour of uncertain differentiation. These tumours are characterized by frequent fusion of the NR4A3 gene with the EWSR1. Extraskeletal chondrosarcoma involving NR4A3-PRRC1 fusion has not been reported before in the literature. Methods: Following routine formaline fixation and tissue pro- cessing, parafin embedded tissues were used for immunohisto- chemical analysis and next generation sequencing. RNA based “Archer® FusionPlex Sarcoma v2” (ArcherDX, Inc) was used to analyse fusions and point mutations in 63 different genes, including NR4A3, in next generation analysis. Results: A 35 years-old female patient presented with weakness in the right leg. On physical examination, a swelling of 8x6cm was detected in the right gluteal region. MRI scan revealed a 156x136mm mass surrounding the right iliac crest and an addi- tional 38x35mm mass at the T12 vertebra level extending into the dural distance. Trucut biopsy revealed a myxoid chondrosarcoma. After 5 cycles of chemotherapy, the patient underwent a right hemi- pelvectomy. Microscopic examination of the resected specimen revealed cords-formed by uniform cells in a myxoid background. NSE and CD117 focally positive in immunohistochemical study. NGS showed fusion of PRRC1 gene with NR4A3 gene. The case was reported as extraskeletal myxoid chondrosarcoma. Conclusion: Along with the previously reported frequent EWSR1 and other rare fusion partners, PRRC1 can also be a fusion partner of NR4A3 in extraskeletal myxoid chondrosarcoma. E-PS-22-003 Two separate metastatic tumours synchronized in the lung: alveolar soft part sarcoma and leiomyosarcoma M. Aydemir*, N. Büyükpınarbaşılı *Health Sciences University Umraniye, Turkey Background & objectives: The lung is a site of widespread metastatic disease, one of the common sites of soft tissue sarcomas. We presented our case because the presence of simultaneous alveolar soft part sarcoma and leimyosarcoma metastases in the lung is rare in the literature. Methods: A 34-year-old female patient was admitted to the pul- monary medicine outpatient clinic due to hemoptysis. Multiple lesions were observed in the lower lobes of both lungs in thorax computed tomography. A total of 4 tumoral foci with two different morphologies were observed in the resection. Results: Microscopically, two of these tumours were spindle cell and the other two were epithelioid with clear/granular cytoplasm. An epithelioid-like tumoral infiltrate with nodules, alveolar pattern, some clear and some pink granular cytoplasm was observed in the parenchyma. In the immunohistochemical and histochemical examination, the epithelioid tumour was positive for TFE-3, and cytoplasmic granular material was positive with PAS and D-PAS. In patient’s history he had been diagnosed with alveolar soft part sarcoma in the left thigh 12 years ago and leimyosarcoma 2 years ago nearthe first lesion. Examination of morphological and IHC profile, it was reported as leiomyosarcoma and alveolar soft part sarcoma metastasis. Conclusion: In the presence of multiple tumours in the lung, it should be kept in mind that there may be different primary tumours or tumour metastases, and all foci should be evaluated. E-PS-22-004 Atypical spindle cell lipomatous tumour: a rare case report J. Baena-Del Valle*, D.M. Bertel-Rodriguez, M.A. Palau-Lazaro *Fundacion Santa Fe De Bogota, Universidad De Los Andes, Colombia Background & objectives: Atypical Spindle Cell / Pleomorphic Lipomatous Tumour (ASCLT) are recently described neoplasms, characterized by lipoma-like appearance but with atypical and spindle cell histological features. They resemble pleomorphic lipoma, but are larger in size and with a broader anatomic distribution. Methods: We present a 34-year-old woman with a 10 x 8 x 3 cm mass in the right knee. A biopsy reported a lipomatous lesion and a resection was performed. Microscopy showed a lipomatous neoplasm with predominantly well-differentiated adipocytic com- ponent, and a smaller proportion of lipoblasts and pleomorphic cells in a fibrous matrix. No necrosis and mitosis were identified. Results: Tumour cells were positive for CD34 and S100, and negative for MDM2 and CDK4. The case was sent for consultation to Dr Christopher Fletcher, supporting the diagnosis of ASCLT. No recurrence has been reported so far. ASCLT mostly occur in middle-aged adults with a slight male pref- erence and a variable size (up to 28 cm). They have an indolent behaviour with no or very low rate of local recurrence, and no risk for dedifferentiation or metastasis. Conclusion: It is crucial to differentiate ASCLT from other lipo- matous lesions such as atypical lipomatous tumour/well-differ- entiated liposarcoma, pleomorphic liposarcoma and low-grade dedifferentiated liposarcoma, due to their frequent recurrence and capacity to metastasize. Immunohistochemistry helps in this situ- ation, since even though weak and focal expression of MDM2 and CDK4 may be seen, they do not occur in combination. Also, loss of Rb expression is frequently seen (79%). E-PS-22-005 Development of epithelioid angiosarcoma as a rare and new complication of retained surgical gauze M. Bara*, F. Almarii, V. Enache *University Emergency Hospital Bucharest, Romania Background & objectives: Epithelioid angiosarcoma (EA) is a rare endothelial cell malignancy. The aetiology is unknown and association with implanted foreign bodies is very rare. We present a case of a 47 year- old woman with EA developed on a long-standing retained surgical gauze. Methods: A 47 year old woman with history of surgery for an ovarian cyst 19 years ago, presented with abdominal pain and constipation for at least 4 days. Clinical examination revealed diffuse tenderness and pain in the lower abdomen and peritoneal signs. Computed tomography (CT) showed a pelvic mass with necrosis and fecaloid content, multiple liver masses and extensive abdominal lymphadenopathy. Results: Gross examination of the surgical specimen revealed 40 cm bowel loops with extensive adhesions, centred by a solid mass of a 10x8 cm tumour with a central cystic cavity containing surprisingly a macerated surgical gauze. A fragment of greater omentum with multi- ple nodules and a mesenteric lymph node were also received. Histologic examination revealed extensive necrosis with a proliferation of pleomorphic epithelioid cells in a storiform pattern and irregular sheets, focally forming anastomosing channels containing few red blood cells. The gauze fibres were also observed. At immunohistochemical examination, the tumour cells showed diffuse expression of CD31, ERG and D2-40. The omentum and the mesenteric lymph node presented also metastatic deposits. S336