Round cell liposarcoma (RCL) and myxoid liposarcoma are now considered as a single pathologic entity for several reasons. Despite many similarities, both morphologic phenotypes may differ considerably, and RCL may be difficult to recognize as liposarcoma. In addition, few cytologic reports describing features of RCL are available.
Five patients with RCL for whom cytologic study of the tumor was available were reviewed. Only tumors in which round cell or poorly differentiated, hypercellular areas comprised > 75% of the tumor were considered RCL.
Smears were hypercellular and consisted of single, round cells with scarce cytoplasm and naked nuclei. Some cells showed slightly oval rather than round nuclei. In three tumors, the background was vacuolated; and, in two tumors, intracytoplasmic vacuoles were present. Isolated fragments of myxoid stroma containing neoplastic cells were identified in two tumors. Pleomorphism was not a prominent finding.
RCL may show morphologic features that are uncommon for a conventional liposarcoma, leading to an erroneous cytologic interpretation. This variant of liposarcoma must be considered when evaluating round cell neoplasms, mainly in adult patients. The presence of oval cells, vacuoles (intracytoplasmic or extracellular), and myxoid stroma should raise this diagnostic possibility, avoiding confusion with other well-known round cell neoplasms. Cancer (Cancer Cytopathol) 2003;99:28–32. © 2003 American Cancer Society.