Groove sign is seen in -
In the secondary stage of LGV when both inguinal and femoral group of lymph nodes are enlarged they are separated by inguinal ligament.( sign of groove,sign of greenblatt). From illustrated synopsis of dermatology and sexually transmitted diseases neena khanna 5th edition page no 330
Donovanosis
LGV
Chancroid
Genital herpes
Sexually transmitted diseases