Hypercellular round cell liposarcoma: A comprehensive cytomorphologic study and review of 8 cases

BACKGROUND: Myxoid and round cell liposarcomas (RCL) are low and high-grade counterparts of a common subtype of liposarcomas (LPS), representing a histologic continuum. AIMS: The aim was to study the cytomorphology of hypercellular RCL and to look for features that differentiate RCL from other sarcomas displaying round cells with myxoid change. MATERIALS AND METHODS: Eight cases of hypercellular RCL were identified retrospectively in which round cell component constituted greater than 75% of the area. Cytomorphological features were studied in detail. RESULTS: Four cases were predominantly composed of round cells, out of which 2 were entirely composed of round cells. Myxoid metachromatic stroma was absent in 2 cases, while it was present in ample amounts in the remaining 6 cases. Spindle cells were completely absent in 5 cases and lipoblasts were observed in a single case of RCL. Plexiform vascular capillaries were seen in 4 cases. Adherence of neoplastic round cells around thin capillaries (ANAC) was observed in 7 cases. CONCLUSIONS: Plexiform capillary plexus and ANAC should be separately evaluated. The latter feature is the most consistent one, and is an important clue to the adipocytic nature of the neoplasm when hypercellular round cell areas are aspirated. Confident diagnosis of hypercellular RCL can be made on the basis of this feature. Lipoblasts, although specific, are seen in few cases. The rest of the features are nonspecific and useful only in combination.