system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 52-year-old Caucasian male presents to your office with an 8 mm dark lesion on his back. The lesion, as seen below, has irregular borders and marked internal color variation. Upon excisional biopsy, the presence of which of the following would best estimate the risk of metastasis in this patient’s lesion:
assistant
Vertical tumor growth