Derm Dx: Dark spots on the lip

A 33-year-old woman requests consultation for dark spots that have been present on her lip for several years. One of the discolorations was biopsied elsewhere and was reported to her as benign. The patient denies antecedent medication use, including minocycline. Examination reveals 2 well-demarcated black macules on her lower lip as well as a similar lesion on the buccal mucosa. ...