Primary mucosal melanoma of the oral cavity: current therapy and future directions

Risk stratification scheme based on the TNM staging system for dogs with oral malignant melanoma centered on clinicopathologic presentation

Introduction

Oral malignant melanoma (OMM) is the most common malignant oral neoplasm in dogs. Tumor recurrence, progression, and regional and distant metastasis remain major obstacles despite advanced therapy. Tumor size has been a consistent, key independent prognostic factor; however, other clinical and histopathologic features impact prognosis and likely influence optimal treatment strategies. Adoption of a risk stratification scheme for canine OMM that stratifies groups of dogs on defined clinicopathologic features may improve reproducible and comparable studies by improving homogeneity within groups of dogs. Moreover, it would aid in the generation of multidisciplinary prospective studies that seek to define optimal treatment paradigms based on defined clinicopathologic features.

Methods

To build a platform upon which to develop a risk stratification scheme, we performed a systematic review of clinicopathologic features of OMM, with particular attention to levels of evidence of published research and the quantitative prognostic effect of clinicopathologic features.

Results

Tumor size and presence of bone lysis were repeatable features with the highest level of evidence for prognostic effects on survival. Overall, with strict inclusion criteria for paper review, the levels of evidence in support of other, previously proposed risk factors were low. Factors contributing to the challenge of defining clear prognostic features including inconsistencies in staging and reporting of prognostic variables, incomplete clinical outcome data, inhomogeneous treatment, and absence of randomized controlled studies.

Discussion

To overcome this in the future, we propose a risk stratification scheme that expands the TNM system to incorporate specific designations that highlight possible prognostic variables. The ability to capture key data simply from an expanded TNM description will aid in future efforts to form strong conclusions regarding prognostic variables and their influence (or lack thereof) on therapeutic decision-making and outcomes.

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

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.

PRAME immunohistochemistry is useful in differentiating oral melanomas from nevi and melanotic macules

BACKGROUND

Oral melanocytic neoplasms pose a diagnostic challenge to pathologists owing to their rarity relative to those in the skin. The utility of PRAME in distinguishing nevi from melanomas has been established in the skin, but limited information exists regarding its usefulness in the oral cavity.

METHODS

Thirty-five previously diagnosed pigmented oral lesions were retrospectively evaluated with PRAME. The lesions consisted of 16 oral nevi, 10 melanomas, and 10 melanotic macules.

RESULTS

Strong and diffuse nuclear PRAME staining was observed in all but one of the oral melanomas, which showed no staining. No nuclear PRAME staining was observed in any of the oral nevi or melanotic macules.

CONCLUSIONS

PRAME is a useful tool in the evaluation of oral melanocytic neoplasms. Our data indicate that PRAME is a highly specific but incompletely sensitive marker of oral melanoma. Larger studies could further illuminate the diagnostic value of PRAME in oral lesions.

Mucosal Melanoma of the Oral Cavity: What is the Role of Elective Neck Dissection?

OBJECTIVES

Mucosal melanoma (MM) is a rare malignancy that can present in the head and neck (H&N). The Oral cavity is the second most common primary site in the H&N after sinonasal mucosa. This study investigates the impact of demographic and clinical factors on survival in oral cavity MM. Further, it investigates the outcomes and utility of elective neck dissections (END) in the management of oral MM.

METHODS

The National Cancer Database was used to evaluate 432 patients with oral cavity MM from 2004 to 2016. Kaplan-Meir and Cox regression analyses were used to determine variables associated with survival.

RESULTS

The mean age was 64.0 ± 16.0 years. Most patients were white (85.1%) and male (60.0%). Gingiva (37.6%) and hard palate (36.1%) were the most common primary subsites in the oral cavity. Five-year overall survival was 31.0%. Age (Hazards Ratio [95% Confidence Interval], 1.03 [1.01-1.06]), N-stage (1.94 [1.10-3.42]), M-stage (10.13 [3.33-30.86]), male sex (1.79 [1.06-3.03]), and African-American race (2.63 [1.14-6.11]) were significantly associated with worse survival. 199 patients (46.9%) underwent neck dissection including 118 with lymph node yield (LNY) ≥ 18. The rate of occult nodal positivity was 45.4% for LNY ≥ 18 and 28.3% for LNY ≥ 1. ENDs were not associated with improved outcomes. However, occult lymph node involvement was associated with worse overall survival (p = 0.004).

CONCLUSIONS

Oral cavity MM has a poor prognosis. Lymph node involvement, distant metastasis, age, race, and male sex are associated with worse outcomes. Performing an END did not improve survival. However, END may have a prognostic role and help select patients for treatment intensification.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:317-326, 2023.

PRAME immunohistochemistry is useful in the diagnosis of oral malignant melanoma

OBJECTIVES

While the incidence of cutaneous melanoma has dramatically increased in recent years, oral malignant melanoma (OMM) remains a rare form of noncutaneous melanoma with poor survival. PRAME (PReferentially expressed Antigen in MElanoma) is reported to have diagnostic and some prognostic utility in cutaneous melanomas and some head and neck malignancies. We sought to explore the diagnostic utility of PRAME in OMM.

METHODS

A total of ten specimens from eight unique cases of OMM were identified from the Oral Pathology Biopsy Service (OPBS) at University of Washington School of Dentistry between 2005 and 2019. For all cases, standard histology and immunohistochemistry stains were performed, including a stain against PRAME. The diagnoses were reviewed and confirmed by two pathologists. Clinical and epidemiologic features were described.

RESULTS

Patient ages ranged from 55 to 82. The group consisted of five males and three females. All eight cases were located on the hard palate. Six cases represented invasive melanoma while two were early melanoma in situ. PRAME immunohistochemistry was successfully performed on seven of eight cases: six were positive (86%), one was negative (14%) and one case lacked sufficient tissue for staining.

CONCLUSIONS

Our results suggest that PRAME immunohistochemistry may be useful in the diagnosis of OMM, including early melanoma in situ. Further studies with clinical follow-up and a larger number of cases are needed to explore prognostic value as well as the ability to distinguish between benign, intermediate and malignant melanocytic proliferations of the oral cavity.

A Large Oral Melanoma: A Case Report of a Rare but Aggressive Malignancy

A variety of black-pigmented lesions of the oral cavity can be found, ranging from harmless benign lesions such as melanotic macule, smoker's melanosis, amalgam/graphite tattoos, and pigmented nevus to a life-threatening oral malignant melanoma. Oral melanoma is a rare and aggressive malignant tumor that originates from melanocytes' proliferation and accounts for only 0.5% of all oral malignancies. The etiology is unknown. Most oral melanomas are present at the palate and the upper alveolar ridge, whereas occurrences at the buccal mucosa, the lower alveolar ridge, and the lip are rare, with only a few reports in the literature. The diagnosis is confirmed by a biopsy. The prognosis is poor, with a 5-year survival rate of ~20%. In this report, we present a case of large oral melanoma at the right buccal mucosa involving the right lower alveolar ridge and lip commissure, which are relatively unusual locations for oral melanoma. In addition, immunohistochemical markers used for diagnostic, therapeutic, and prognostic decision-making of oral melanoma are also discussed.

Mucosal Melanoma of the Hard Palate: Surgical Treatment and Reconstruction

Mucosal melanomas of the head and neck region are uncommon pathologies that can affect the oral cavity, and are characterized by a high rate of mortality. Considering the lack of knowledge regarding risk and prognostic factors, current best clinical practice is represented by a large surgical excision with disease-free margins, eventually associated with a reconstructive flap. Indeed, given the frequent necessity of postoperative radiotherapy and fast healing process, a reconstruction of the surgical gap is advisable. Even if several flaps have been most commonly used, the submental island flap represents a valid alternative thanks to local advantages and similar oncologic outcomes compared to free flaps.

Pigmented Lesions

Oral pigmented lesions have a wide range of clinical presentations, some of which correlate with cutaneous pigmented lesions. This article highlights these correlates and underscores important differences that can potentially have clinical impact. Moreover, given a nonspecific presentation of an oral pigmented lesion, the article provides a reference to aid clinicians with differential diagnoses based on clinical features. This article is an overview of pigmented lesions of the oral cavity, including localized reactive pigmented lesions, neoplastic pigmented lesions, and pigmented lesions as sequelae of a systemic disease.

Oral Melanomas: A Case Series of a Deadly Neoplasm

PURPOSE

To describe and discuss the demographic and clinical features of oral melanomas, which are relatively rare but deadly neoplasms, and list the criteria for their diagnosis to increase early detection.

MATERIALS AND METHODS

An institutional review board-approved retrospective search of oral melanomas was performed in the archives of the University of Florida Oral and Maxillofacial Pathology Biopsy Service (Gainesville, FL) from 2015 through 2018. Exclusion criteria included cases with inconclusive diagnosis, skin involvement, and missing clinical data or slide material. Of 7 patients with a diagnosis of melanoma of the head and neck region, 6 (87.5%) were found to be diagnosed with oral melanomas and met the inclusion criteria.

RESULTS

All 6 patients were at least 45 years (range, 45 to 87 yr). The male-to-female ratio was 4:2. Three patients were asymptomatic and 3 experienced symptoms, including pain, swelling, and tingling. Seven lesions were detected in these 6 patients. Three of these lesions were located on the maxillary gingiva, 2 were on the mandibular gingiva, and 2 involved the palate. Two lesions were diagnosed as spindle cell melanoma, 4 were diagnosed as melanoma, and 1 was diagnosed as a mucosal lentiginous melanoma.

CONCLUSION

Oral melanomas should be considered in the differential diagnosis of oral pigmented lesions, especially on the gingiva or palate, in middle-age and elderly patients. Oral melanomas have a male bias. In addition, supportive criteria enabling early diagnosis of oral melanomas is addressed.

A comprehensive genome-wide analysis of the long noncoding RNA expression profile in metastatic lymph nodes of oral mucosal melanoma

BACKGROUND & AIM

Oral mucosal melanoma (OMM) is a kind of malignancy with extremely rare morbidity. It exhibits a poorer biological behavior and clinical outcome compared with cutaneous melanoma. lncRNAs are endogenous cellular RNA transcripts with no protein-coding potential and are associated with oncogenesis through cis- or trans-acting mechanisms. Despite increased evidence that proved lncRNAs have vital roles in tumorigenesis of mucosal melanoma, little is known about their functions in the progress of lymph node dissemination of OMM.

METHOD

Here, we constructed a lncRNA and mRNA microarray using six metastatic lymph nodes and paired-matched non-metastatic lymph nodes. Then, we performed RT-PCR to validate the microarray data both in primary and metastases. We further constructed lncRNA and mRNA co-expressing networks and analyzed the biological functions by Gene Ontology (GO) and pathway analyses for dysregulated lncRNAs and mRNAs. Cis- and trans-regulation analysis were also performed to explore the specific mechanism of lncRNAs in OMM.

RESULT

Our results showed that 570 lncRNAs were upregulated with 292 lncRNAs downregulated in the metastatic OMM tissues. The results of RT-PCR were consistent with our microarray dataset both in primary and metastases. Gene Ontology (GO) and pathway analyses indicated that they play an important role in the melanin biosynthetic process, new growing cell tip and lysosomes in metastatic OMM. In the cis-regulation analysis, we observed metastasis-associated gene, PLEKHA5, the cis gene of lnc-AEBP2-1_1 and lnc-AEBP2-2_1, and microphthalmia-associated transcription factor (MITF), the cis gene of SAMMSON_3, SAMMSON_5 and lnc-MITF-5_1. In the trans-regulation analysis, CTBP2 and SUZ12 regulated lncRNA expression in the core TF-lncRNA-gene network.

CONCLUSION

Our results suggest that lncRNAs may be involved in the metastasis of OMM, and further investigation is needed to focus on the biological functions and the underlining molecular mechanisms exerted by these dysregulated lncRNAs in OMM.

A Review of the Aetiopathogenesis and Clinical and Histopathological Features of Oral Mucosal Melanoma

Oral mucosal melanoma is an uncommon, usually heavily melanin-pigmented, but occasionally amelanotic aggressive tumour with a poor prognosis. Despite radical surgery, radiotherapy, or chemotherapy, local recurrence and distant metastasis are frequent. Microscopical examination is essential for diagnosis, and routine histological staining must be supplemented by immunohistochemical studies. The aetiology is unknown, the pathogenesis is poorly understood, and the 5-year survival rate rarely exceeds 30%. In most cases, oral mucosal melanoma arises from epithelial melanocytes in the basal layer of the epithelium and less frequently from immature melanocytes arrested in the lamina propria. In both cases the melanocytes undergo malignant transformation, invade deeper tissues, and metastasize to regional lymph nodes and to distant sites. Very rarely metastasis from skin melanoma may give rise to oral mucosal melanoma that may be mistaken for primary oral mucosal melanoma. The pathogenesis of oral mucosal melanoma is complex involving multiple interactions between cytogenetic factors including dysregulation of the cKit signalling pathways, cell cycle, apoptosis, and cell-to-cell interactions on the one hand and melanin itself, melanin intermediates, and local microenvironmental agents regulating melanogenesis on the other hand. The detailed mechanisms that initiate the malignant transformation of oral melanocytes and thereafter sustain and promote the process of melanomagenesis are unknown.

[Pigmentations of the oral cavity]

Buccal mucosa color is explained by hemoglobin in the vessels and melanin in the epithelium. Abnormal presence of melanin pigments (hypermelaninosis, hypermelanocytosis), hematic pigments (hemoglobin, hemosiderin, iron) but also some exogenous circonstancies explain pigmented lesions (figure 1). These lesions could be localized (single lesions), multifocal (multiple lesions) or diffused. In case of a localized pigmentation with melanic appearance, melanoma must be systematically eliminated with a biopsy. In the case of a more diffused lesion, systemic disease must be evoked. A drug etiology is also possible. A blood pigment excess could be a vascular malformation (flat lesions) or a tumoral process (nodular or swollen lesions). In both cases, Kaposi's disease should be systematically eliminated. Pigmentations near dental restorations (amalgams, prosthetic crowns) could be explained by an exogenous factor but a biopsy should be performed in case of a doubt with melanoma.