Pathogenesis and clinicohistopathological caractheristics of melanoacanthoma: A systematic review

Comparative evaluation of six commercial adult toothpaste formulations reveals cytotoxicity and altered functions in a human oral melanocyte model: an in vitro study

This study aims to compare six commercial adult toothpaste (labeled as A, B, C, D, E, and F) for cytotoxicity and melanocyte function alterations in vitro using primary human epidermal melanocytes from a Caucasian donor (HEMn-LP cells) as a model of oral melanocytes. Cells were incubated with toothpaste extracts (50% w/v) in culture media at dilutions (1:25, 1:50, 1:100, 1:200, 1:500, 1:800, and 1:1000) for 24 h. MTS and LDH assays were used to assess cytotoxicity. The effects of noncytotoxic toothpaste concentrations on melanocyte functional endpoints were then examined using spectrophotometric methods. All toothpaste showed concentration-dependent cytotoxicity that was heterogeneous across toothpaste containing SLS detergent. IC50 values of cytotoxicity followed the order: A = E > C > B > D > F. To compare toothpaste, they were tested at 1:800 and 1:1000 dilutions that were noncytotoxic after 24 h. None of the toothpaste affected cellular melanin production. However, toothpaste A, C, and D suppressed tyrosinase activity at both dilutions, while toothpaste B suppressed tyrosinase activity only at 1:800 dilution. Toothpaste A, C, E, and F elevated ROS production at 1:800 dilution, with no change at 1:1000 dilution. Toothpaste has a heterogeneous effect on melanocytes. Toothpaste B, E, and F at 1:1000 dilution were the safest as they did not alter melanocyte functions at this dilution, although toothpaste F is the least cytotoxic of these. Future studies are necessary to expand these results in a physiological environment of oral tissue. The findings of this study provide novel insight into the biocompatibility studies of toothpaste on oral melanocytes. They can aid dental practitioners and consumers in selecting noncytotoxic toothpaste that do not contribute to ROS generation by melanocytes in the oral cavity or lead to cytotoxicity and impaired cellular function.

Oral melanoacanthoma: Clinicopathological and immunohistochemical features of a case series and a scoping review

BACKGROUND

This study presents a case series and scoping review of oral melanoacanthoma to examine its clinical, histopathological, and immunohistochemical characteristics.

METHODS

Nine cases of oral melanoacanthoma were included in the case series. Clinical data were collected from biopsy charts. Hematoxylin-eosin and immunohistochemistry for TRP2, CD3, and CD20 were done. For the scoping review, MEDLINE/PubMed, Web of Science, EMBASE, and Scopus were searched.

RESULTS

Case series: The mean age was 46.8 years (female-to-male ratio 2:1). Lesion's mean size was 11.0 mm (±9.3). Lesions were mainly macular (77.8%) with brown or black coloration (88.9%) and often affected multiple sites (44.4%). The evolution time ranged from 15 days to 96 months. Lesions commonly showed epithelial acanthosis (66.7%), spongiosis (55.6%), exocytosis (77.8%), melanin incontinence (88.9%), and inflammatory infiltrate in the lamina propria (77.8%), from which all showed lymphocytes. TRP2-positive melanocytes were identified in the basal and spinous layer of all cases, and in the superficial layer of three cases. CD3-positive cells predominate over the CD20-positive. Scoping review: 85 cases of oral melanoacanthoma were retrieved from 55 studies. Patients were primarily female (female-to-male ratio 2.2:1), black-skinned (64.1%), with a mean age of 36.13 (± 17.24). Lesions were flat (81.9%), often brown (62.4%). Buccal mucosa was the preferred site (32.9%), followed by multiple sites (28.2%).

CONCLUSION

Oral melanoacanthoma mainly affects women across a wide age range, with lesions commonly appearing as brown/black macules, particularly on the buccal mucosa. TRP2-positive melanocytes and T-lymphocytes were consistently found and could participate in oral melanoacanthoma pathogenesis.

Habitual khat chewing and oral melanoacanthoma: A case report

BACKGROUND

Habitual khat (Catha edulis) chewing has been proven to cause numerous oral tissue changes. However, oral melanoacanthoma triggered by chronic khat chewing is rare. Oral melanoacanthoma is an uncommon, sudden, asymptomatic, benign pigmentation of the oral cavity. Under the microscope, the epithelial layer of the oral mucosa showed dendritic melanocyte proliferation and acanthosis. The study aimed to highlight chronic khat chewing as a trigger for oral melanoacanthoma.

CASE SUMMARY

In the current study, we report a case of a 26-year-old male patient with a rare presentation of oral melanoacanthoma triggered by regular khat chewing. Many intrinsic and extrinsic factors can cause oral pigmentation. Chewing khat is an extrinsic factor that can cause several diseases, including oral pigmentation. In this case, the definitive diagnosis was oral melanoacanthoma. This diagnosis was made based on the patient’s history, clinical lesion presentation, and microscopic biopsy results.

CONCLUSION

Habitual khat (Catha edulis) chewing causes many oral tissue changes including oral melanoacanthoma. The study aimed to highlight chronic khat chewing as a trigger for oral melanoacanthoma.

New Approach to Addison Disease: Oral Manifestations Due to Endocrine Dysfunction and Comorbidity Burden

This review highlights oral anomalies with major clinical impact in Addison disease (AD), including dental health and dermatologic features, through a dual perspective: pigmentation issues and AD comorbidities with oral manifestations. Affecting 92% of AD patients, cutaneomucosal hyperpigmentation is synchronous with or precedes general manifestations by up to a decade, underlying melanocytic infiltration of the basal epidermal layer; melanophages in the superficial dermis; and, rarely, acanthosis, perivascular lymphocytic infiltrate, and hyperkeratosis. Intraoral pigmentation might be the only sign of AD; thus, early recognition is mandatory, and biopsy is helpful in selected cases. The buccal area is the most affected location; other sites are palatine arches, lips, gums, and tongue. Pigmented oral lesions are patchy or diffuse; mostly asymptomatic; and occasionally accompanied by pain, itchiness, and burn-like lesions. Pigmented lingual patches are isolated or multiple, located on dorsal and lateral areas; fungiform pigmented papillae are also reported in AD individuals. Dermoscopy examination is particularly indicated for fungal etiology; yet, it is not routinely performed. AD’s comorbidity burden includes the cluster of autoimmune polyglandular syndrome (APS) type 1 underlying AIRE gene malfunction. Chronic cutaneomucosal candidiasis (CMC), including oral CMC, represents the first sign of APS1 in 70–80% of cases, displaying autoantibodies against interleukin (IL)-17A, IL-17F ± IL-22, and probably a high mucosal concentration of interferon (IFN)-γ. CMC is prone to systemic candidiasis, representing a procarcinogenic status due to Th17 cell anomalies. In APS1, the first cause of mortality is infections (24%), followed by oral and esophageal cancers (15%). Autoimmune hypoparathyroidism (HyP) is the earliest endocrine element in APS1; a combination of CMC by the age of 5 years and dental enamel hypoplasia (the most frequent dental complication of pediatric HyP) by the age of 15 is an indication for HyP assessment. Children with HyP might experience short dental roots, enamel opacities, hypodontia, and eruption dysfunctions. Copresence of APS-related type 1 diabetes mellitus (DM) enhances the risk of CMC, as well as periodontal disease (PD). Anemia-related mucosal pallor is related to DM, hypothyroidism, hypogonadism, corresponding gastroenterological diseases (Crohn’s disease also presents oral ulceration (OU), mucogingivitis, and a 2–3 times higher risk of PD; Biermer anemia might cause hyperpigmentation by itself), and rheumatologic diseases (lupus induces OU, honeycomb plaques, keratotic plaques, angular cheilitis, buccal petechial lesions, and PD). In more than half of the patients, associated vitiligo involves depigmentation of oral mucosa at different levels (palatal, gingival, alveolar, buccal mucosa, and lips). Celiac disease may manifest xerostomia, dry lips, OU, sialadenitis, recurrent aphthous stomatitis and dental enamel defects in children, a higher prevalence of caries and dentin sensitivity, and gingival bleeding. Oral pigmented lesions might provide a useful index of suspicion for AD in apparently healthy individuals, and thus an adrenocorticotropic hormone (ACTH) stimulation is useful. The spectrum of autoimmune AD comorbidities massively complicates the overall picture of oral manifestations.

Multifocal Intraoral Melanoacanthomas: Two Case Reports and a Literature Review

Intraoral melanoacanthoma is a rare, reactive pigmented lesion that is mostly seen in black individuals with a tendency to occur more frequently in younger females. The color of melanoacanthoma may vary from brown to black, and it is commonly seen as a solitary lesion in the buccal mucosa. This lesion requires no treatment, and no malignant potential has been observed to date. The clinical presentation of multifocal oral melanoacanthoma (MOMA) (the rate of growth and the recurrence) is usually diagnostic. On the other hand, solitary oral melanoacanthoma might be difficult to diagnose, and a biopsy should be performed and examined by a well-trained oral pathologist. Here, we report two cases of MOMA with an unusual location in one case.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Tumours of the Oral Cavity and Mobile Tongue

The fifth chapter of the upcoming fifth edition of the 2022 World Health Organization Classification of Tumours of the Head and Neck titled Tumours of the oral cavity and mobile tongue, has had some modifications from the 2017 fourth edition. A new section "Non-neoplastic Lesions", introduces two new entries: necrotizing sialometaplasia and melanoacanthoma. The combined Oral potentially malignant disorders and Oral epithelial dysplasia section in the 2015 WHO has now been separated and submucous fibrosis and HPV-associated dysplasia are also discussed in separate sections. Carcinoma cuniculatum and verrucous carcinoma are described in dedicated sections, reflecting that the oral cavity is the most common location in the head and neck for both these entities which have distinct clinical and histologic features from conventional squamous cell carcinoma. This review summarizes the changes in Chapter 5 with special reference to new additions, deletions, and sections that reflect current clinical, histological, and molecular advances.

A Unique Presentation of Gingival Melanoacanthoma: Case Report and Review of Literature

Melanoacanthoma is a benign, deeply pigmented condition of the oral mucosa characterized by the proliferation of melanocytes and keratinocytes. A 60-year-old male, with no history of systemic diseases or medical treatment, presented with an asymptomatic diffuse pigmentation involving the maxillary and mandibular gingiva. The histopathology of the anomalous pigmented area was analyzed and the dendritic melanocytes expressed positively for Masson-Fontana, S-100, and HMB-45. The clinical and microscopic findings were indicative of melanoacanthoma. Depigmentation with a diode laser was performed in the areas of esthetic concern. A regular periodic screening was done to rule out any alteration in color, size, and shape. A one-year follow-up disclosed no new lesions. The observations noted in this case are rare, and our literature review identified only a single previously documented case of gingival melanoacanthoma in the Indian subpopulation.

Clinical and histopathological study of the oral multifocal melanoacanthoma: A case report

Melanoacanthoma is a blackened mucocutaneous lesion, mainly affecting individuals with dark skin and exhibiting rapid development. Differential diagnosis includes nevus, amalgam tattoo and melanoma. This article reports a case of a 53-year-old white woman, who exhibited multiple blackened lesions on the gingiva and upper lip. After incisional biopsy, the presence of numerous melanin-containing dendritic cells distributed throughout the epithelial thickness, which were S-100 (+), were observed microscopically. Final diagnosis was multifocal oral melanoacanthoma. Follow-up for 28 months has shown appearing of more lesions in gingiva and upper lip. Therefore, the importance of differential diagnosis of oral melanoma with the group of oral pigmented lesions, and possible associated systemic diseases were evaluated.

Key words:Melanocytes, pigmentation, oral mucosa, gingiva, differential diagnosis.

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

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.