Differential Diagnosis of Pigmented Lesions in the Oral Mucosa: A Clinical Based Overview and Narrative Review

Abstract

This paper examines the clinical differentiation of pigmented lesions in the oral mucosa, which poses significant diagnostic challenges across dental and medical disciplines due to their spectrum from benign to potentially malignant conditions. Through a literature review and analysis of clinical cases, this study clarifies current diagnostic methodologies, with an emphasis on differential diagnosis, to provide a practical guide for clinicians. The classification of pigmented lesions, such as endogenous, focal melanocytic, and multifocal pigmentation, based on clinical and histological features, highlights the necessity for a structured and informed approach. A retrospective examination of cases from our oral medicine and pathology clinic, coupled with analysis of photographic and histological records, aids in classifying these lesions. This fosters a better understanding and promotes informed discussions among clinicians, ultimately aiming to enhance early and precise diagnosis, thus improving patient management and outcomes.

Keywords: malignant melanoma; melanin; mouth mucosa; oral health; oral medicine; oral pathology; oral pigmentation; pigmented lesions.

Figure 1

Ephelides on the perioral skin and labial psudomucosae on a 22-year-old patient. Patient refers to these lesions from birth. (archive S.A., patient signed the consent for clinical pictures).

Figure 2

Oral melanotic macula on the lower labial vestibular mucosa on a 7-year-old patient. Parents referred these lesions as being present for over 6 months. (archive S.A., patient signed the consent for clinical pictures).

Figure 3

Oral melanotic macula on the upper gingival mucosa on a 40-year-old patient. Patient refers to these lesions as being present since over 6 months. (archive S.A., patient signed the consent for clinical pictures).

Figure 4

Ethnic pigmentation of the gingival tissues on a 60-year-old patient. Patient refers to these pigmentation from decades. (archive S.A., patient signed the consent for clinical pictures).

Figure 5

Oral malignant melanoma, in the hard palatal mucosa on a 67-year-old female patient. Patient refers to these lesions as being present for 3 months. (archive S.A., patient signed the consent for clinical pictures).

Figure 6

Smoker’s Melanosis in the lower gingival mucosa of a 38-year-old heavy smoker male patient. Patient refers to these lesions as being present for 6 years. (archive S.A., patient signed the consent for clinical pictures).

Figure 7

Grayish-blue dark pigmentation at the border between hard and soft palate due to hemosiderin deposition in a 65-year-old female patient affected by beta-thalassemia. Patient refers to these lesions as being present for 10 years. (archive S.A., patient signed the consent for clinical pictures).

Figure 8

The so-called “amalgam tatoo”, greyish pigmentation of the marginal gingival from particles of an amalgam of the previous dental restoration of upper premolar teeth sprayed during the preparation of the prosthetic abutments in a 67-year-old patient. Patient refers to these lesions as being present for 20 years. (archive S.A., patient signed the consent for clinical pictures).

Figure 9

Extensive oral mucosal pigmentation due to long term therapy with systemic hydroxychloroquine in a 70-year-old patient. Patient refer to these lesions as being present for over 10 years. (archive S.A., patient signed the consent for clinical pictures).

Figure 10

Labial ephelides in a woman affected by Peutz–Jeghers Syndrome in a 63-year-old patient. Patient refer to these lesions as being present for 45 years. (archive S.A., patient signed the consent for clinical pictures).

Figure 11

Pigmentation of the cheek mucosa in a patient with Addison’s disease in a 35-year-old female patient. Patient refer to these lesions as being since years. (archive S.A., patient signed the consent for clinical pictures).

Figure 12

Area of tongue mucosa pigmentation in a patient with reticular oral lichen planus in a 42-year-old male patient. Patient refers to these lesions as being present for several years. (archive S.A., patient signed the consent for clinical pictures).