Cytologic features of sarcomas in fluids

Sarcomas account for < 6% of malignant effusions and their diagnosis usually is made in the setting of a known primary tumor. However, these tumors often exhibit a variety of features that can differ from those of the original neoplasm and may preclude the correct diagnosis. This article evaluates the cytomorphology of sarcomas in fluids and determines characteristic features for identification and classification.

The study included 24 Papanicolaou-stained fluid samples (15 pleural, 8 peritoneal, and 1 pericardial) from patients with a diagnosis of sarcoma. The following features were evaluated: cellular arrangement, cellularity, nuclear/cytoplasmic ratio, background, quality and quantity of cytoplasm, cell borders, and nuclear details.

All cytology specimens were diagnosed accurately as malignant. The histopathologic diagnoses were eight malignant fibrous histiocytomas, five leiomyosarcomas, three rhabdomyosarcomas, three liposarcomas, two high grade sarcomas, one osteogenic sarcoma, one synovial sarcoma, and one chondrosarcoma. Cytomorphologic features shared by sarcomas in metastatic sites included single cell arrangement (23 of 24; 95.8%), indistinct cell borders (18 of 24; 75.0%), nuclear pleomorphism (18 of 24; 75.0%) multinucleation (13 of 24; 54.2%), and proteinaceous background with lysed blood (17 of 24; 70.8%).

Sarcomas in effusions share morphologic features that allow their correct diagnosis. Further subclassification can be attempted in the proper clinical setting and by comparison with the primary lesion.