Epithelioid sarcoma is a peculiar
soft-tissue neoplasm of uncertain origin, which is characterized by an epithelioid morphology of
tumor cells coexpressing epithelial (
keratin) and nonepithelial (
vimentin)
antigens. We herein report a new
cytogenetic abnormality with der(22)
t(18;22)(q11;p11.2) in a case of
epithelioid sarcoma that occurred in the elbow of a 75-year-old man. Histologically, the
tumor demonstrated a multinodular proliferation of epithelioid cells, with positive immunostaining for
keratin,
epithelial membrane antigen (EMA), and
vimentin. Cultured tumor cells obtained from fresh surgical materials were frozen in
plastic ampules and stocked in a liquid
nitrogen freezer. Six years after surgery, the cells were recovered from the freezer and utilized for both morphologic and cytogenetic analyses. These cultured cells both before and after the freezing exhibited essentially the same epithelioid morphology and immunophenotypes as those of the original
tumor. A chromosome analysis, together with fluorescence in situ hybridization (FISH), demonstrated a 61-67 modal population, and a characteristic clonal abnormality with der(22)
t(18;22)(q11;p11.2). Other clonal abnormalities included numerical (-3, -4, +7, -13, -14, -16, -18, +20, -22) and structural (8p+, 9p+, 12p+, i(21q)) aberrations. Some variant clones also demonstrated i(18q). Since the breakpoint at 18q11 is similar to that reported in
synovial sarcoma, this finding may support the presence of a histogenetic relationship between
epithelioid sarcoma and
synovial sarcoma. Our study thus indicates that the storage of frozen cells is useful for both morphologic and cytogenetic analyses of soft tissue
tumors.