Tuberous Sclerosis Adenoma Sebaceum

A 12-year-old boy with a 2-year history of seizures and mild intellectual disability presents to the dermatology clinic. On examination, he has multiple symmetric small reddish-brown papules distributed over his nasolabial folds and cheeks, as marked **A** in the diagram. His mother reports that these lesions first appeared around age 4 years. Brain MRI reveals cortical tubers and subependymal nodules. Based on the clinical presentation and the facial lesions marked **A**, which of the following best explains the underlying pathogenesis of these skin manifestations in this patient?