The fine needle aspiration of translocation sarcomas

IntroductionSoft tissue sarcomas comprise a heterogeneous group of clinically aggressive cancers that are often hard to classify on limited cytological samples. Translocation sarcomas (TS) are a diverse subset of such cancers, different from pleomorphic sarcomas, and characterised by unique single chromosomal translocations in each sarcoma subtype. Interestingly, despite their high-grade biological behaviour, TS have deceptively monotonous and bland cytomorphology, therefore creating diagnostic issues on limited samples. Materials and methodsA retrospective search was conducted of the cytopathology archives of The Johns Hopkins Hospital revealing 147 translocation sarcoma cases over a 25-year period. ResultsThe common morphological denominators for most translocation sarcomas were: hypercellularity, cellular monotony, mostly discohesive and single cells, round-to-oval or short spindled cells and a lack of necrosis. The exceptions were an inflammatory myofibroblastic tumour, in which cellular monotony was not present owing to the prominence of lymphocytes and plasma cells, and low-grade fibromyxoid sarcoma, in which the specimens were generally hypocellular. Ancillary testing, especially immunoperoxidase staining, was often required for primary lesions. ConclusionDistinct morphological clues and subsequent ancillary testing (particularly immunoperoxidase staining) provide an accurate diagnosis on cytological interpretation of both, primary and recurrent/metastatic lesions. While the morphology and specific genetic translocations vary among the different types of translocation sarcomas, translocation sarcomas are known to share one common feature: they often appear bland and monotonous, and this appearance may distract from their otherwise malignant nature. While this understanding is well established in many surgical pathology reports, the cytomorphological features have only been described in smaller case series and individual case reports. In this study, we describe the cytomorphological features of 147 translocation sarcomas as seen on fine needle aspiration at our institution over a 25-year period.