A 40-year-old, chronically ill man from a Vietnamese village presents with painful sores around his mouth. Physical examination reveals prominent fissures at the angles of his mouth. Cheilosis in this patient is most likely caused by a deficiency of which of the following vitamins?

Cheilosis refers to fissures at the angles of the mouth and is a common finding in patients with vitamin B2 (riboflavin) deficiency Riboflavin participates in the synthesis of flavin mononucleotides. Seborrheic keratosis and interstitial keratitis of the cornea also occur in patients with vitamin B2 (riboflavin) deficiency. Except for vitamin A deficiency (which does not cause cheilosis), the other choices (B, D, and E) do not affect the skin.Diagnosis: Cheilosis, vitamin B2 (riboflavin) deficiency