6th February 2024

A 45-year-old male presents with a 3-month history of watery diarrhoea without any blood or mucous.

A 45-year-old male presents with a 3-month history of watery diarrhoea without any blood or mucous. He does not have any associated abdominal pains or fevers. He is a known heavy alcohol drinker, and his wife reports a longstanding poor diet. Examination reveals multiple dry, cracked patches along the arms and legs. Further patches of rash are seen along her neck in a collar-like appearance. A beefy, red tongue was noted. AMT was 10/10. He is noted to have a vitamin B deficiency as the underlying cause. 

Which of the following is the likely underlying diagnosis?