The "circle of hebra" represents the main sites of involvement in
Circle of Hebra: Imaginary circle intersecting sites of predilection in Scabies ie; Areolae, axillae, elbow flexures, wrists, finger webs, umbilicus, lower abdomen, genitalia. Ref Harrison 20th edition pg 1244
Blister beettle dermatitis
Pediculosis corporis
Scabies
Toxoplasmosis
Bacterial infections