Francis, a 51-year-old laboratory technician of Asian descent, presents initially with a one-month history of scaly, itchy rash on his right palm. He is unable to identify any triggers. There is no known past history of any skin conditions, and family history is unremarkable. He works in a laboratory handling chemicals and washes his hands frequently throughout the day with soap and water. There are no pets in his household, and he has had no recent exposure to new soaps, moisturisers, detergents or washing liquids.

Francis is otherwise well, takes no regular medications, has no known allergies, does not smoke and drinks alcohol very occasionally. He lives with his wife and two daughters.

On examination, there is a 2cm diameter scaly erythematous plaque over the thenar eminence of his right hand (pictured). The rest of his physical examination is unremarkable. 

He is given a provisional diagnosis of contact dermatitis, likely secondary to frequent handwashing at work. He is prescribed topical mometasone 0.1% cream and given advice about general skin care measures to help management and prevent recurrence.

Francis re-presents four months later with the same complaint. He reports he experienced only transient reduction in itch and redness with application of the topical steroid, but never any resolution of his symptoms. He has used up his entire 15g tube of topical steroid in the meantime. He also reports now experiencing a stinging discomfort in the region of the rash with repeated handwashing.