Pathology of the Head and Neck

Oral Cavity Chapter 3 89tropic hormone (ACTH) secretion. Parts of the skin exposedto the sun and areas subjected to trauma or frictionbecome bronzed [85]. There is also increased pigmentationin skin folds and scars. About 10% of patientsalso show areas of vitiligo.Oral pigmentation is variable and where presentranges from light brown to densely black [95]. The gingiva,lateral margins of the tongue, buccal mucosa andlips are the sites of predilection. Microscopy of the areasshows increased melanin predominantly in the basalkeratinocytes.3.5.5 Peutz Jeghers SyndromePeutz Jeghers syndrome (periorifacial lentiginosis)comprises melanotic spots of the face, mouth and lesscommonly the hands and feet, together with intestinalpolyposis. It is inherited as an autosomal dominant traitwith nearly complete penetrance [93], but new mutationsoccur in 40% of cases.There are multiple ephelides on the face and melanoticmacules in the mouth involving the lower labialand buccal mucosa in particular. Lesions are oftenpresent at birth. The facial pigmentation is around themouth, nose and eyes and tends to progressively fadeafter puberty. The mucosal pigmentation persists intoadult life.There are hamartomatous polyps throughout the intestinaltract, but typically these are most numerous inthe small intestine. They can give rise to abdominal painand bleeding and intussusception is a rare complication.The polyps have a low malignant potential, with thosein the colon having the highest risk. Patients also are atincreased risk of malignancy at other sites including theuterus, ovary, pancreas and breast.3.5.6 Racial PigmentationRacial pigmentation is the most common cause of intraoralpigmentation. It is seen predominantly in Blacks,Asians and people of Mediterranean origin, but about5% of Caucasians also have significant intraoral pigmentation.The degree and extent of racial pigmentationis very variable and does not necessarily correlate withthe depth of skin pigmentation. It can vary from lightbrown to almost black and the most commonly involvedsites are the gingiva, palate and buccal mucosa. Sometimeswhen the tongue is involved the only areas affectedare the fungiform papillae, producing an appearanceof spotty pigmentation.Microscopy shows increased melanocytic pigmentationof the basal and, to a much lesser degree, the immediatelysuprabasal keratinocytes. The denser pigmentationis due to increased synthesis of melanin by melanocytes,which are otherwise normal in number and distribution.3.5.7 Laugier Hunziker SyndromeLaugier Hunziker syndrome is an acquired, benignmacular hyperpigmentation of the lips and oral mucosa[118]. It typically starts in early to middle adult life andis more common in women than men. The pigmentationconsists of brownish, circular or linear macules,that may be sharply circumscribed or more diffuse innature, and lesions may coalesce. The lesions are seenmost commonly on the buccal mucosa, lips and thehard and soft palates. Other less frequent sites includethe tongue, gingiva and floor of the mouth. Occasionally,the pharynx and oesophagus are also involved[190]. About half of the cases also have nail involvementin the form of longitudinal pigmented bands inone or more fingers or toes. There are no known systemicassociations.Microscopy shows increased melanotic pigmentationof basal keratinocytes and melanophages in the superficialcorium secondary to pigmentary incontinence. Ultrastructuralstudies show increased numbers of normal-appearingmelanosomes in keratinocytes in thelower epithelial layers [118].3.5.8 Smoker’s MelanosisHeavy smokers can sometimes develop areas of oralhyperpigmentation. It is more common in womenthan men. Although any part of the mouth can beaffected the anterior gingivae are involved most frequently.The lesions vary in colour from light brownto bluish-black and the lesions may be focal or diffuse.Sometimes the overlying mucosa has a somewhatmilky-white appearance, particularly in the buccalmucosa. The condition can slowly resolve if smokingis stopped or reduced [72]. Pigmentation of the softpalate has been reported in a significant number ofpatients with suppurative lung disease and malignancy[117]. Nearly a quarter of patients with confirmedbronchogenic carcinoma show this feature. Most patientshave a long history of cigarette smoking and it ispossible that in many cases these lesions were merelysmoker’s melanosis rather than being related directlyto the pulmonary lesions.Microscopy may show slightly increased melanoticpigmentation of the basal keratinocytes, but the moststriking feature is usually pigmentary incontinence andaccumulation of melanophages in the superficial corium.