ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Conclusion: Myelolipoma is an uncommon benign tumour composed of adipose tissue and normal hematopoietic elements, which incidence is 0,08-0,2%. We present 10 cases of extraadrenal myelolipomas. Extraadrenal myelolipoma is a rare benign and asymptomatic tumour that may be misdiagnosed as a malignant lipomatous tumour on radio- logical studies. Most of them are incidentally detected during radio- logical investigation of unrelated symptoms. Surgery is the recom- mended treatment. The final diagnosis relies on pathologic findings. PS-10-006 Anastomosing haemangioma with unusual location and mim- icking malignancy: a case series and literature review E. Dicle Serbes*, E. Gedik, S. Yuksel, G. Kaygusuz *Ankara University Medical School, Pathology Department, Turkey Background & objectives: Anastomosing haemangioma (AH) is a relatively newly defined entity seen mostly in the kidney. Extrarenal localizations have also been reported. Herein, we report two non-renal cases, one of which is the second case in English literature involving anterior mediastinum. Methods: Excisional biopsies were obtained from a 68-year-old woman with an anterior mediastinal mass (8 mm), and a 41-year- old man with a mass of 12.5 mm located between left adrenal gland and tail of pancreas. The latter had a pre-diagnosis of a malignancy. Both of them was incidentally found. Radiological examinations including CT, MRI and PET scans were also evaluated. Results: Both lesions were un-encapsulated, well-circumscribed tumours consisting of predominantly small, anastomosing, splenic-like sinusoidal vascular structures which were lined by single layer of flat endothelial cells with occasional hobnail cells. Small fibrin thrombi was present in some vascular chan- nels. No multilayering of endothelial cells, cytological atypia, necrosis, mitotic activity, extramedullary haematopoiesis or invasion into surrounding tissues was found. Immunohistochem- ically, tumour cells were diffusely positive with CD31, ERG and CD34 but negative for GLUT1, D2-40, Desmin or Cytokeratin. Ki67 proliferation index was lower than 5% in tumour cells. Cases were diagnosed as AH. Anterior mediastinal AH had posi- tive surgical margins, the patient has been following for 2 years without any local recurrence. Conclusion: Anastomosing haemangioma is a relatively newly described benign vascular tumour. It is a rare neoplasm which can have some overlapping histologic features with well-differ- entiated angiosarcoma. It was originally described in kidney and perinephric adipose tissue in 2009, but extrarenal sites including testis, spermatic cord, ovary, adrenal glands, gastrointestinal tract, mesentery, soft tissues and bone had also been reported. Recogni- tion of this entity and knowing that it may occur in unexpected localisations may help it’s differential diagnosis from more aggres- sive lesions. PS-10-007 Three cases of Kaposi sarcoma as initial manifestation of HIV infection and AIDS J. Jevtic*, L. Simic, R. Janković, S. Rajkovic, G. Djuricic, J. Sopta *Institute of Pathology, Serbia Background & objectives: Epidemic Kaposi sarcoma (KS), the most common subtype, is seen in the setting of HIV infection and related acquired immunodeficiency. We report three cases of KS as initial manifestation of AIDS. Methods: We analysed medical records from Register of bone and soft tissue lesions biopsies in the Institute of pathology, Medical Faculty, University of Belgrade from 2006 to 2022. Results: Only three patients had KS associated with HIV infec- tion as initial manifestation of AIDS. All of them were males. One patient was 40-year-old with KS localized in tonsil, and two of them were 43-year-old with KS localized in cervical lymph nodes. All patients were presented with bulky masses and all of them underwent excisional biopsy. Histological analysis showed spin- dle cell tumour, without pleomorphism, mixed with inflammatory cells. Aforementioned spindle cells were immunohistochemically positive for vascular markers. Positivity for HHV-8 indicated diag- nosis of KS and further clinical examinations in order to confirm/ exclude AIDS were performed. All patients were found to be HIV positive, with developed AIDS. Conclusion: Even though rare, KS could be initial manifestation of AIDS. In order to confirm/exclude the diagnosis of KS, when there are any histological suspicion, HHV-8 should be applied. Early diagnosis of KS and AIDS prevents complications and ensures better prognosis. PS-10-008 Pediatric chordomas: report of five cases with emphasis on poorly differentiated subtype and SMARCB1/INI1 deficiency Z.B. Erdem*, A.M. Onenerk Men, S.N. Tuter, S. Ocak, N. Comunoglu *Basaksehir Cam and Sakura City Hospital, Turkey Background & objectives: Chordoma is a rare primary malignant bone tumour showing notochordal differentiation. They usually affect adults, and extremely rarely seen in paediatric age group. For children, such tumours present a different biology with aggressive histological features, and worse prognosis. Methods: All chordomas diagnosed between January 2016-January 2022 in one institution were reviewed for the study (total number of 41). Five patients belonging to paediatric age group were found and included in the study. Results: Patients ages ranged between 2 to 18 years(median:9 years); 3 females, 2 males. Tumour localizations were as follows: two cervical vertebrea, two clivus and one intracranial(cerebellopontin angle). On histomorphologic exami- nation, three cases showed conventional chordoma features, one of them was compatible with chondroid chordoma and two of the cases had poorly differentiated morphology. On immunohis- tochemical analysis all tumours showed cytokeratin and EMA positivity. Four tumours showed S100 positivity with one of the poorly differentiated tumours being negative. Four of the tumours were brachyury positive (wasn’t applied to one of the conventional chordoma). SMARCB1(INI1) immunohistochemistry was applied to all and both of the poorly differentiated tumours showed loss of expression. Conclusion: Currently, WHO classifies chordomas into three sub- types: conventional, poorly differentiated, dedifferentiated. Fea- tures in paediatric population are different from the correspond- ing adult tumours. Majority of “poorly differentiated” tumours are found in children and diagnostic feature of this subtype is loss of SMARCB1(INI1) expression. Demonstration of bracyury positiv- ity with loss of SMARCB1(INI1) expession are easily applica- ble diagnostic tests. Although the limited data on poorly differ- entiated chordomas show that they have poor prognosis, proving SMARCB1(INI1) loss provides an opportunity for possible targeted therapies. S120