Final answer:
John, a construction worker, has noticed a change in the color of a nevus on his shoulder from brown to bluish black. The advised action is to consult a doctor regarding the nevus as it may be a sign of melanoma.
Step-by-step explanation:
John, age 49, is a construction worker and has noticed a change in color of a nevus on his shoulder from brown to bluish black. This change in color may indicate a potential sign of melanoma, a type of skin cancer. Melanomas often present as large brown or black patches with uneven borders and a raised surface.
Given the change in color and the description of the nevus, it is important for John to consult a doctor as soon as possible. Early detection and treatment of melanoma is crucial for better outcomes.
Therefore, you advise John to consult a doctor without delay to assess the nevus on his shoulder and determine any necessary further steps.