Desmoid tumors are associated with as many as 20% of cases of familial
adenomatous polyposis (FAP) and Gardner's syndrome. In the present st
udy, four specimens from different regions of a massive intraabdominal
desmoid tumor from a a 3-year-old white male with Gardner's syndrome
were analyzed cytogenetically. Two different clonal abnormalities were
observed. Two of the four specimens analyzed showed a del(5)(q14q31),
which involves the region q21-->22 where the familial adenomatous pol
yposis gene is localized. In the two other specimens, a balanced trans
location involving chromosomes 3 and 4 and an inv(4) was detected. Our
findings confirm previous reports about the importance of chromosome
defects on 5q in development of desmoid tumors, particularly in patien
ts with Gardner's syndrome.