Oedema present for more than 3 months which is not fully resolved by overnight elevation
Cellulitis more common (2)
Sources:
(1) C Moffatt et al. Prevalence and Risk Factors for Chronic Edema in U.K. Community Nursing Services. Lymphatic Research and Biology. Volume 17, Number 2, 2019
(2) E.A. Burian et al. Cellulitis in chronic oedema of the lower leg: an international cross-sectional study. British Journal of Dermatology (2021) 185, pp110–118
COS can point you in the right direction