Ahmad Faizal bin Rahman, a 42-year-old man, presents with a mildly itchy skin lesion over his right forearm that he first noticed about three weeks ago. The lesion has gradually increased in size despite the use of a moisturising cream. He works as a security guard and often wears long-sleeved uniforms for prolonged periods, particularly during night shifts. There is no history of trauma, insect bites, recent travel, or contact with new soaps or chemicals. He is otherwise well and has no known chronic medical illnesses.
On examination, there is a single, well-demarcated erythematous plaque on the extensor aspect of the forearm with fine peripheral scaling and relative central clearing. There is no associated pain, discharge, or surrounding cellulitis. No other skin lesions are noted. His vital signs are stable: temperature 36.8°C, blood pressure 124/76 mmHg, pulse rate 72 beats per minute and regular.
A skin sample is taken from the edge of the lesion and examined. Microscopy finding is as shown:
