ECP 2023 Abstracts

S177 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 E-PS-04-011 False positive clinical-radiological hyperprogression due to sarcoid- like granulomatosis in neoadjuvant treatment of locally advanced lung cancer J. Martin Lopez*, P. Gil Bernabé, S. Martin Poza, G. Diaz Nuevo, G. Silvestre Egea, C. Salas Anton *Department of Pathology. Hospital U. Puerta de Hierro, Spain Background & objectives: Sarcoid-like granulomatous reaction is a rare effect of some drugs used in the treatment of locally advanced LC. Some patients treated with neoadjuvant immunotherapy show radio- logically abnormal nodes that upon pathological evaluation are free of cancer and show non-caseating granulomas. Methods: 67-year-old man, ex-smoker with a 7.7 cm lung mass diag- nosed by bronchial biopsy of squamous cell carcinoma, stage cT4N0. He started neoadjuvant treatment with Carboplatin / Taxol plus Pem- brolizumab. Radiological follow-up tests described a new ipsilateral lesion (SUVmax of 6.3) and hiliar and mediastinal lymphadenopathy. Given the suspicion of disease progression, EBUS and mediastinos- copy were performed. Results: The EBUS-guided ROSE identified a sarcoid-type gran- ulamatous reaction that was later confirmed by preoperative medi- astinoscopy. At this time, a pulmonary lobectomy was proposed and accepted by the patient. The histopathological evaluation of the surgi- cal specimen revealed areas of cavitation and necrosis that accounted for 60% of the neoadjuvant bed with an inflammatory reaction in the form of collagen fibrosis and a lymphocytic-type infiltrate with the presence of multinucleated giant cells with cholesterol crystals. Viable neoplastic cellularity was not observed. In the peritumoral, septal, and pleural areas, the presence of diffusely distributed granulomas of sarcoid morphology stood out. A diagnosis of complete pathological response with extensive associated sarcoid reaction was made. Conclusion: The administration of combined chemotherapy-immunother- apy is showing clear benefits in the treatment of locally advanced lung cancer (stage III). Neoadjuvant immunotherapy can lead to the presence of para- doxical effects of disease progression in patients who develop sarcoid-like reactions. Our case exemplifies how cytological interpretation in these cases is really useful in diagnosing these reactions. Also, the histopathological study of the specimen allows the determination of the degree of pathological response, which is not always predictable on radiological studies. E-PS-04-012 Metastatic vulvar adenocarcinoma associated with a long-stand- ing Paget disease diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA): a case report of a rare entity C. Mora*, J. Ferreira, R. Fonseca *Serviço de Anatomia Patológica, Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisbon, Portugal Background & objectives: Vulvar adenocarcinoma associated with Paget Disease is an uncommon occurrence (<2% of all vulvar malig- nancies) and distant metastasis are even rarer (only 2,5% of all cases reported). Given the rarity of this entity, diagnosis remains a challenge. Methods: We herein report a case of a 75 year-old woman with a long- standing diagnosis (22 years) of vulvar Paget disease, who underwent multiple surgical and topic therapies, without ever having histological evidence of invasive disease. Then, because of new onset haematuria and lumbar pain she was restudied thoroughly. Results: On evaluation, thoraco-abdomino-pelvic CT identified mul- tiple mediastinal adenopathies and pulmonary nodules. EBUS-TBNA of a lymph node was performed. Smears were hypercellular, with tri- dimensional aggregates of epithelial cells with irregular nuclei and dense vacuolated cytoplasm, positive for CK7, GDCFP15, androgen receptor (AR) and ERBB2 (score 3+), and negative for CK20 and TTF1. Additional staging scans excluded a mammary origin. A new vulvar biopsy was performed, where an identical adenocarcinoma with CK7, GATA3, AR expression, and ERBB2 positivity was documented. A diagnosis of metastatic vulvar adenocarcinoma associated with Paget Disease was rendered. With rapidly evolving symptoms and “de novo” bone and liver metastasis, the patient died one month later. Conclusion: Vulvar Paget Disease is a rare but generally indolent cuta- neous neoplasm, in which relapse is common but metastases, espe- cially distant metastases, are very rare. Due to its rarity, the cytological diagnosis of metastatic vulvar adenocarcinoma associated with Paget disease can be challenging, especially in distant locations. Neverthe- less, careful clinical correlation and immunohistochemistry can help overcome this difficulty. E-PS-04-013 Fine needle aspiration cytology of a fibrin-associated diffuse large B-cell lymphoma arising in retroperitoneal pseudocyst: a case report K. Na*, H. Kim *Department of Pathology, Kyung Hee University Hospital, Kyung Hee University College of Medicine, Republic of Korea Background & objectives: Fibrin-associated diffuse large B-cell lymphoma (FA-DLBCL) is an unusual form of DLBCL associated with chronic inflammation. FA-DLBCL is frequently associated with Epstein-Barr virus (EBV) and manifests as non-mass-forming, micro- scopic lesions found within fibrinous material. Methods: A 72- year-old male presented with a large retroperitoneal cyst. The mass was completely resected by a laparoscopic approach. Cystic fluid was aspirated right after surgical resection and sent to the pathology laboratory for cytological examination. The resected tis- sue was submitted for histological examination. Fibrinous exudate and necrotic material attached to inner cystic wall was collected for cell block preparation. Results: Papanicolau stain for the cytological specimens showed singly dispersed large atypical cells in a necrotic background. These atypical cells possessed scant cytoplasm, hyperchromatic nuclei with irregular nuclear contours, vesicular chromatin and inconspicuous nucleoli. Fre- quent karyorrhexis and mitotic figures were noted. Histologically, the cystic lesion consisted of thick fibrous wall with heavy lymphoplasma- cytic infiltration. The fibrinous exudate contained large atypical cells that were individually scattered or arranged in small clusters. Frequent karyorrhectic debris and mitotic figures were noted. Immunostain- ing revealed that the atypical lymphoid cells were positive for CD20, MUM1, and EBER-ISH but negative for CD3, Bcl-6, CD10, and HHV8. Conclusion: FA-DLBCL is cytologically characterized by the presence of large atypical cells individually scattered in a necrotic background. They have scant cytoplasm and irregular, hyperchromatic nuclei. Kary- orrhexis and mitotic figures are easily identifiable. To the best of our knowledge, this is the first case report describing the cytological fea- tures of FA-DLBCL. E-PS-04-014 Challenges & pitfalls in rapid onsite evaluation of salivary gland lesions using Milan system for reporting salivary gland cytopathol- ogy (MSRSGC); experience from Lahore, Pakistan F. Rehman*, A. Nawaz, M.U. Farooq, R. Saqib, K. Shehzadi, A. Hamid, A. Aftab *Associate professor Pathology department, Ameerudin medical col- lege/postgraduate medical institute, Lahore, Pakistan Background & objectives: ROSE is used to achieve adequate amount of aspirated material from suspected lesion. Milan System provides stand- ardized reporting in salivary gland cytopathology. The aim of this study is to determine the challenges faced during ROSE of salivary Gland lesions.