Black and Brown: Non-neoplastic Pigmentation of the Oral Mucosa

Abstract

Black and brown pigmentation of the oral mucosa can occur due to a multitude of non-neoplastic causes. Endogenous or exogenous pigments may be responsible for oral discoloration which can range from innocuous to life-threatening in nature. Physiologic, reactive, and idiopathic melanin production seen in smoker's melanosis, drug-related discolorations, melanotic macule, melanoacanthoma and systemic diseases are presented. Exogenous sources of pigmentation such as amalgam tattoo and black hairy tongue are also discussed. Determining the significance of mucosal pigmented lesions may represent a diagnostic challenge for clinicians. Biopsy is indicated whenever the source of pigmentation cannot be definitively identified based on the clinical presentation.

Keywords: Biopsy; Black; Brown; Melanin; Melanotic; Oral mucosa; Pigmentation.

Fig. 1

a Diffuse, homogenous brown pigmentation of the attached gingiva. b Physiologic pigmentation of the fungiform papillae. c Post-inflammatory pigmentation of the dorsal tongue in a patient with erosive lichen planus

Fig. 2

Diffuse light brown pigmentation affecting the buccal mucosa (a) and ventral tongue (b) in a patient with Addison’s disease

Fig. 3

Multiple small, dark brown macules on the lip vermillion and perioral skin of a patient with Peutz–Jeghers syndrome (photo courtesy of Dr. Robert Brannon)

Fig. 4

a Multiple brown macules on the labial mucosa of a patient with Laugier–Hunziker syndrome (photo courtesy of Dr. Carl Allen) and b toenail exhibiting melanonychia

Fig. 5

Drug-related discoloration: symmetric gray/black pigmentation of the posterior hard palate in a patient taking hydroxychloroquine for the treatment of systemic lupus erythematosus

Fig. 6

a Melanotic macule at the wet–dry line of the lower lip. b Melanotic macule of the interdental papilla between #8 and #9. c Histopathologic features of melanotic macule demonstrating increased melanin within the basal layer and incontinent melanin within the lamina propria

Fig. 7

a Melanoacanthoma of the upper labial mucosa. b Histopathologic features of melanoacanthoma showing dendritic melanocytes dispersed throughout acanthotic stratified squamous epithelium and incontinent melanin within the lamina propria

Fig. 8

Light brown pigmentation of the mandibular anterior gingiva in a Caucasian female who reported smoking one pack of cigarettes per day for 40 years

Fig. 9

a Clinical appearance of an amalgam tattoo. b Radiographic findings in same patient from a. c Histopathology of amalgam tattoo showing staining of reticulin fibers around small blood vessels. d Intentional gingival tattooing in an African female

Fig. 10

Hairy tongue with brown pigmentation