Pigmented, brown or black lesions

Published on March 29, 2017   53 min

Other Talks in the Series: Oral & Maxillofacial Medicine

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My name is Dr. Sook-Bin Woo, and I am Associate Professor at the Harvard School of Dental Medicine. The topic for this lecture is Pigmented, Brown or Black Lesions of the Oral Cavity.
Pigmentations can occur from either an exogenous sources, which means outside the body, or from an endogenous source, which means inside the body. The most common exogenous sources of pigmentation are foods that we eat every day, so things like coffee and tea that we drink will often cause staining of the teeth. Other very common exogenous pigments that can cause lesions in the oral cavity include amalgam, graphite, medications that are taken, ritual tattoos that occur in some cultures in the world, as well as imbibing heavy metals for whatever reason. Endogenous pigments are those that are produced by the cells within the body and the two most common are melanin pigment produced by melanocytes, which are often found on the skin and also of coarse within the oral epithelium as well as blood-related pigments, and these are related primarily to the break down of red blood cells. I just wanted to mention an interesting chemical called homogentisic acid, which is a phenolic acid that is produced in the body or accumulates in the body in patients with alkaptonuria which is poorly controlled, and this causes very dark pigmentation of many organs in the body. But we're not going to talk about that today. It's just sort of an interesting side note.
Let's start by talking a little bit about extrinsic pigmentation that refers to pigmentation that lies on the surface of the mucosa or on the surfaces of teeth. So these are exogenous as well as extrinsic. The most common are foods that are pigmented, so drinking lots of tea and coffee, or smoking cigarettes, chewing areca nut in all its forms, and using chlorhexidine mouthwash will often cause a brownish black pigmentation on the surfaces of the teeth. The other very common sight for extrinsic pigmentation of exogenous origin is the staining of the tongue, and this gives rise to a condition called a coated or hairy tongue that is black or brown usually because of pigment from foods, whether this is a natural pigment of the food or whether the food has been dyed. Pigmented tongue can also be caused by bacterial products. The tongue has many bacteria on its surface and the metabolites of these bacteria are often sulfites, and as we know, most sulfites are black. So very often the tongue will have a black appearance and that's called a black hairy tongue. Patients who take a lot of Pepto-Bismol or bismuth subsalicylate for dyspepsia will also often see a black pigmentation on the tongue because of the bismuth which is a heavy metal.