A 17-year-old boy comes to the office for evaluation of a rash. For the past 2 years, the patient has had recurrent skin bumps that are frequently red and painful. He has no other medical conditions and takes no medications. Vital signs are within normal limits. Skin examination findings are shown below. 
This patient's skin condition primarily affects which of the following structures?
Definitions:
Daily Operating Time
The total time per day during which a business or system is operational and open for business.
Cycle Time
The total time from the beginning to the end of a process, indicating the time taken to complete a single cycle of an operation.
Operating Time
The total time during which a machine, system, or facility is functioning and available for use.
Fabrication Lines
Assembly lines specifically designed for the manufacturing and assembling of products from raw materials or components.
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