Oral pigmented lesions: a retrospective analysis from Brazil

Abstract

Background: Pigmented lesions are uncommon in the oral mucosa, and studies investigating the incidence and types of these lesions are desired to improve the diagnostic knowledge of clinicians. The aim of this study was to analyze the distribution of oral pigmented lesions in a Brazilian population.

Material and methods: A retrospective descriptive cross-sectional study was performed. Oral pigmented lesions were retrieved from the files of two oral and maxillofacial pathology services from Brazil over a 45-year period (1974-2019). The clinical data and the diagnoses of each case were retrieved and included in a Microsoft Excel® database.

Results: From 77.074 lesions diagnosed in this period, 761 (0.99%) represented pigmented lesions of the oral mucosa, including 351 (46.1%) melanocytic and 410 (53.9%) non-melanocytic lesions, with a higher incidence in females (73.2%) between the fourth and seventh decades of life. Amalgam tattoo (53.6%) represented the most common lesion, followed by melanotic macule (18.3%) and racial pigmentation (10.8%). Other pigmented lesions included nevus (9.9%), post-inflammatory pigmentation (3%), melanoma (2.1%), melanoacanthoma (1.4%), smoker's melanosis (0.4%), drug-induced pigmentation (0.3%), and melanotic neuroectodermal tumor of infancy (0.1%). The buccal mucosa was the most commonly affected site (25.2%), followed by the alveolar ridge (14.5%), and gingiva (11.8%).

Conclusions: The current findings were similar to previous studies with minor differences due methodology and characteristics of the services from where lesions were retrieved. The knowledge of these data may contribute to a better understanding of oral pigmented lesions and assist clinicians to better recognize and manage them.

Figure 1

Oral pigmented lesions detected in the study.

Figure 2

A. Distribution of 761 oral pigmented lesions according to the age group (decade of life) and B. primary site of involvement. NI, not informed.

Figure 3

Clinical and histopathological features of oral pigmented lesions. A. Amalgam tattoo located in the transition between buccal mucosa and lower lip. B. Presence of fine black and brown amalgam particles along collagen bundles and around blood vessel (Hematoxylin and eosin, 400X). C. Melanotic macule in the lower lip presenting as a small and well-circumscribed, brown macule. D. Increased production of melanin by melanocytes located in the basal layer (Hematoxylin and eosin, 400X). E. Oral melanocytic nevus located in the left buccal mucosa. F. Presence of pigmented nevus cells in the lamina propria (Hematoxylin and eosin, 400X).

Figure 4

Clinical and histopathological features of oral pigmented lesions. A. Blue nevus in the hard palate. B. Presence of spindle melanocytes in deep portion of the connective tissue (Hematoxylin and eosin, 200X). C. Melanoacanthoma in the right buccal mucosa. D. Presence of pigmented dendritic melanocytes throughout the epithelium (Hematoxylin and eosin, 400X). E. Gross appearance of an incisional biopsy of oral melanoma with darkish cut surface and fibroelastic consistency. F. Proliferation of malignant melanocytes with melanin production (Hematoxylin and eosin, 400X).