<prompt> All are precanerous exceptLichen planusVerrucous carcinomaSubmucous fibrosisLeukoplakia  <response>: Verrucous carcinoma is a squamous cell carcinoma, commonly occurring in mucous membrane or muco- cutaneous junction without lymph node spread. It is dry, exophytic, way, indurated growth. It has good prognosis. It is a curable malignancy. Surgery is the treatment--wide excision;No radiotherapy used. Leukoplakia is a white patch in the mucosa of the oral cavity that cannot be characterised clinically or pathologically to any other disease. It is the most common and is a high risk premalignant condition of oral cavitydefinite risk of malignant change. Oral submucosal fibrosis is a medium risk premalignant condition of oral cavitypremalignant but not assw higher incidence of carcinoma. 4.5-7.6 of oral submucosal fibrosis turns into malignancy.Oral lichen planus is a premalignant lesion of oral cavity with equivocal risk.Reference : page 369 and 370 SRBs manual of surgery 5th edition 