<prompt> Child with recurrent mouth ulcer which usually begin as a round yellowish elevated spot surrounded by a red halo and heals within 7-10 days:GingivitisAphthous ulcersMalignancyHerpetic ulcer  <response>: Ans.: b Aphthous ulcersRef.: Harrisons 19th ed. 239 Apthous ulcers are also called as canker soresapthous stomatitis and present as round ulcer with yellowish base and surrounded by a red halo. The usual sites are oral mucosa on the insides of lips , cheeks or below the tongue. Most of apthous ulcers are 5mm in size and heal within 1-2 weeks. Painless recurrent apthous ulcers are seen in SLE Painful recurrent apthous ulcers in oral cavity and genitilia is seen are in Behcet disease 