Cytomorphologic Features of Metastatic Sarcomas in Body Cavity Fluids Overlaps with Other Common Malignancies

Abstract

Background: Sarcomas rarely involve body cavity fluids, accounting for less than 5% of all malignant effusions. Most existing literature describes the cytomorphologic features of sarcomas in the setting of fine-needle aspiration and/or touch preparations of targeted tissue biopsies. The objective of this study was to investigate the morphologic spectrum displayed by metastatic sarcomas in body cavity fluid specimens. Methods: The pathology database at our institution was searched for sarcoma cases involving pleural, pericardial, and peritoneal fluids between 1994 and 2019. Their clinical presentations and cytopathologic features were reviewed. Immunohistochemical (IHC) stains were performed on the cellblock sections at our institution on the DAKO Autostainer (DAKO, Carpinteria, CA). Results: Nineteen cases were identified, including 14 females and 5 males, ranging in age from 4 to 88 years old (median: 28.6 years). The body cavity sites were 11 pleural, 7 peritoneal, and 1 pericardial. There were 5 rhabdomyosarcomas, 4 osteosarcomas, 4 Ewing sarcomas, 2 endometrial stromal sarcomas, 2 leiomyosarcomas, 1 clear cell sarcoma, and 1 liposarcoma. Malignant pleural effusion was the first presentation in only 2 cases (both alveolar rhabdomyosarcomas). Three different cytomorphologic patterns were seen: 1-glandular cell pattern showing large epithelioid cells with vacuolated cytoplasm (3 cases), a 2-pleomorphic single-cell pattern showing large highly atypical cells (6 cases); 3-small round blue cell pattern showing small to intermediate-sized dyscohesive cells with high NC ratio (10 cases). Conclusion: The cytomorphologic spectrum exhibited by metastatic sarcomas in body cavity fluids often overlaps with other common malignancies such as metastatic adenocarcinomas, poorly differentiated carcinomas, and lymphomas. Keywords: Sarcoma; Cytology; Peritoneal.