Pigmented Lesions of the Oral Mucosa Pocket Dentistry Differential Diagnosis of Pigmented Lesions in the Oral Mucosa: A Clinical Based Overview and Narrative Review COM Dec. 2011 Diagnosis UW School of Dentistry Definition of melanocytic macules associated with Peutz Jeghers syndrome NCI Dictionary of Genetics Terms NCI Brown spots, especially on the lips, can be alarming to some. In some instances it can indicate rare oral mucosal melanoma, however in this case it was a non cancerous labial melanotic macule.