Method: Microsatellite analysis of loss of heterozygosity (LOH) has been used to identify clonality of tumors. This study analyzed one rare oral sarcomatoid squamous cell carcinoma by using both immunohistochemical straining (pankeratin and vimentin) and LOH assay with primers on chromosomes 3p14 (3p1234, 3p1300, 3p1228, 3p1285), 8p (8p261, 8p262, 8p264), 9p21 (9pINFA, 9p1751, 9p1748, 9p171), and 17p (tp53, 17p786, CHRNB).
Result: The patient died 10 weeks after the diagnosis. The carcinomatous component stained positive for keratin but negative for vimentin; whereas the sarcomatous component stained positive for vimentin with only occasional focal positivity for keratin. Both of the components showed an identical LOH pattern, loss at 3p14, 9p21 (regarded to be essential and early for development of oral squamous cell carcinoma) and 8p (associated with the aggressiveness of head and neck carcinoma). All of the markers for 17p were noninformative.
Conclusion: The study results for the first time provide genetic evidence supporting that the dimorphic components of the tumor are from the same molecular clone.