Lichen planus is indeed a long standing condition in some. If not immunosuppressants, you'll need immuno modulators or other anti inflammatory or drugs like dapsone. However all these medications need to be prescribed under due examination by a dermatologist and regular monitoring. Non steroidal topical medication is also available. Thick lesions on legs do require local steroid injection and respond well to it if given properly in the right plane of the skin lesion. Let me know if you need any further assistance in this regard. Take care.