ECP 2023 Abstracts

S252 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 The carcinoma cells formed parodic, irregular glandular spaces popu- lated by pleomorphic, dys-cohesive cells, with large, irregular nuclei, prominent nucleoli and eosinophilic to focally clear cytoplasm. There was luminal shedding of cells. No lympho-vascular or myometrial inva- sion was observed in the endometrial polyp. The background endome- trium was non-atrophic. The immuno-profiles for both carcinomas included diffuse, (mutated type) p53 positivity, p16 overexpression and concordant expression patterns for other markers. Conclusion: This case having several instructive oddities, under- pins the inherently aggressive nature of uterine serous carcinoma, notwithstanding the tumour volume or extent of involvement at the primary site. The fact that this clinico-pathological denouement unfolded in a 43 year old pre-menopausal patient is an admonition to practicing cellular pathologists, to ratchet their index of suspicion low, for the possibility of this variant, even in patients that are much younger than those in which it is conventionally thought to occur. E-PS-10-002 Frequency of placental histopathological lesions: a retrospective study in a tertiary hospital L. Aguirrezabal Marcotegui*, S. Fernández Ferrer, A. Tarín Nieto, J. Roselló Soria, I. Fernández de la Prieta, C. Valentí Ponsa, G. Cancho Galán, A. Nogueira Gegrorio *Hospital Universitario de Basurto, Bilbao, Spain Background & objectives: The placenta is one of the most poorly understood organs and its examination often presents an intimidating task for the general pathologist. The objective of this study is to deter- mine the frequency and type of histopathological lesions in placentas. Methods: This retrospective systematic search included 660 placental samples received in a tertiary hospital between 2018 and 2022. Lesions were classified into the following categories: amniotic fluid infection sequence (maternal and foetal inflammatory response), maternal vas- cular malperfusion, foetal vascular malperfusion and other lesions. Depending on the histological findings, the placentas could be classi- fied in more than one category. Results: The 50,1% of the placentas did not present any significant findings. The amniotic fluid infection sequence diagnose was the most prevalent, observed in 31,5% of the placentas. The 14,4% had maternal vascular malperfusion lesions, being infarcts the 70,5% of this cat- egory. Foetal vascular malperfusion was diagnosed in the 1% of the placentas. The rest of the lesions comprised the 9,1% of diagnoses (chronic inflammatory lesions, retroplacental hematomas, chorangi- osis, meconium-stained placenta and single umbilical artery among others). To be emphasized two cases os placenta accreta, one congenital leukaemia and one malaria infection. Conclusion: Most frequent diagnoses were amniotic fluid infections and infarcts. However, in 50,1% of the placentas no histopathological lesions were found. It would be interesting to know, if the absence os lesions in half of studied placentas is due to the lack of training of general surgical pathologist, or if it is necessary to review the clinical criteria used to send placental samples for histological examination. E-PS-10-003 Pulmonary metastasis of a TTF-1 positive endometrial endometrioid carcinoma – a case report V. Almeida*, B. Sepodes, C. Courelas, J. Gama, V. Sousa, L. Carvalho *Institute of Anatomical and Molecular Pathology, Faculty of Medicine of the University of Coimbra, Portugal, CIMAGO – Research Center for Environment, Genetics and Oncobiology, Faculty of Medicine, University of Coimbra, Portugal, Pathology Service, University Hos- pital Anatomical Pathology Coimbra, Portugal Background & objectives: Thyroid transcription factor-1 (TTF-1) is a reliable marker for primary lung adenocarcinoma, while it is rarely expressed in endometrial carcinomas. We report a TTF-1 positive endometrioid carcinoma (EC) of the endo- metrium with metastatic lung disease. Methods: A 64 years-old non-smoker woman with a history of endo- metrial endometrioid carcinoma FIGO grade 3, staged as FIGO 1A, was treated with hysterectomy with lymphadenectomy and adjuvant vaginal brachytherapy. Two years later, she presented with respiratory distress, and the imaging study suggested bilateral cannonball metastases. A transthoracic biopsy directed to the largest lung nodule was performed. Results: The lung biopsy revealed an adenocarcinoma with a predomi- nantly solid growth pattern, and also tightly constricted microacinar struc- tures. Tumoral cells were large cells with nuclei enlargement and atypia. On immunohistochemistry, the tumour showed strong positivity for nuclear PAX8 and cytoplasmatic vimentin; p53 had a wild-type pattern, and oes- trogen receptors were negative. Nuclear TTF-1 was diffusely expressed. We reviewed the primitive endometrial carcinoma slides and retrospec- tively performed a TTF-1 stain, which was also diffusively positive. The final diagnosis was pulmonary metastasis of EC of the endome- trium with aberrant TTF-1 expression. Conclusion: Less than 10% of ECs express TTF-1, with higher rates in the G3 subset, as in this case. TTF-1 expression in EC has also been associated with a worse prognosis. TTF-1 positive ECs metastasizing to the lung can be challenging to dis- tinguish from primary lung adenocarcinoma. It is important to remem- ber that TTF-1 may be immunoreactive in gynaecologic malignancies, and that the correct diagnosis frequently depends on both clinical cor- relation and immunostaining with multiple antibodies. E-PS-10-004 Cotyledonoid dissecting leiomyoma of the uterus: a case report showcasing concomitant mitotically active ovarian thecoma A. Ardelean*, G. Stefanet, M. Boros, E.M. Popescu *Pathology Department - County Clinical Emergency Hospital Bihor, Romania Background & objectives: Cotyledonoid dissecting leiomyoma (CDL) and mitotically active thecoma are rare variants of their otherwise com- mon counterparts, each with their own unique clinical, paraclinical and microscopic diagnostic challenges. We aim to advance knowledge on these entities and facilitate further diagnosis. Methods: We present a case of a 63-year-old woman with cotyledonoid dissecting leiomyoma of the uterus and concomitant mitotically active ovar- ian thecoma. The patient presented to our hospital due to lower abdominal pain and fecal incontinence. Clinical and paraclinical examination revealed a fibromatous uterus with compressive phenomena. The patient underwent surgery for total hysterectomy and bilateral salpingo-oophorectomy. Results: Grossly the uterus presented with a micronodular, cauliflower and placenta-like mass that extended towards the left ovary. Microscopi- cally it showed proliferation of short-length smooth muscle fascicles that dissected the myometrium and extended outside of the uterus. Cells were positive for oestrogen, progesterone, desmin, and SMA, negative for CD10 and with a Ki67 proliferation index lower than 5%. Micro- scopic examination of the ovary revealed a multilobulated thecoma with one outstanding well-circumscribed nodule showing medium to large polygonal cells with variable nuclear pleomorphism and numer- ous mitoses. All thecoma lobules showed positivity for Wt1, SMA, MelA and Calretinin, while being negative for MCK. Reticulin staining showed well demarcated cell borders.