Over a 12-year period (1979-1991), 29 cases of Sweet's syndrome (SS) w
ere detected in the area of Geneva; 24 patients (82%) could be contact
ed for follow-up. The majority of SS occurred between 1979 and 1986, t
hen from 1991 on. The annual distribution and especially the absence o
f cases during 4 years suggest an environmental or even infectious fac
tor in SS. Only 4 cases had an underlying disease (ulcerative colitis,
polycythemia, lymphoma, sarcoidosis) whereas in the other, a long-ter
m follow-up, including iterative hematological evaluation, did not rev
eal any underlying condition. Twelve patients were treated by colchici
ne, 9 by potassium iodide and 5 by prednisone; in 3 patients remission
was spontaneous. Nine patients (28%) relapsed; there was no relations
hip between the type of drugs used and the frequency of relapses.