A rare case of amelanotic malignant melanoma in the oral region: Clinical investigation and immunohistochemical study

Interleukin-4 induced 1-mediated resistance to an immune checkpoint inhibitor through suppression of CD8+ T cell infiltration in melanoma

Cancer cells adopt multiple strategies to escape tumor surveillance by the host immune system and aberrant amino acid metabolism in the tumor microenvironment suppresses the immune system. Among the amino acid-metabolizing enzymes is an L-amino-acid oxidase called interleukin-4 induced 1 (IL4I1), which depletes essential amino acids in immune cells and is associated with a poor prognosis in various cancer types. Although IL4I1 is involved in immune metabolism abnormalities, its effect on the therapeutic efficacy of immune checkpoint inhibitors is unknown. In this study, we established murine melanoma cells overexpressing IL4I1 and investigated their effects on the intratumor immune microenvironment and the antitumor efficacy of anti-programmed death-ligand 1 (PD-L1) antibodies (Abs) in a syngeneic mouse model. As a result, we found that IL4I1-overexpressing B16-F10-derived tumors showed resistance to anti-PD-L1 Ab therapy. Transcriptome analysis revealed that immunosuppressive genes were globally upregulated in the IL4I1-overexpressing tumors. Consistently, we showed that IL4I1-overexpressing tumors exhibited an altered subset of lymphoid cells and particularly significant suppression of cytotoxic T cell infiltration compared to mock-infected B16-F10-derived tumors. After treatment with anti-PD-L1 Abs, we also found a more prominent elevation of tumor-associated macrophage (TAM) marker, CD68, in the IL4I1-overexpressing tumors than in the mock tumors. Consistently, we confirmed an enhanced TAM infiltration in the IL4I1-overexpressing tumors and a functional involvement of TAMs in the tumor growth. These observations indicate that IL4I1 reprograms the tumor microenvironment into an immunosuppressive state and thereby confers resistance to anti-PD-L1 Abs.

Oral Amelanotic Melanoma: A Systematic Review of Case Reports and Case Series

Oral amelanotic melanoma (OAM) is a rare, non-pigmented mucosal neoplasm representing less than 2% of all melanoma. The present study analyses the available data on OAM and describes its clinicopathological features, identifying potential prognostic factors. Online electronic databases such as PubMed-Medline, Embase, and Scopus were searched using appropriate keywords from the earliest available date till 31st March 2021 without restriction on language. Additional sources like Google Scholar, major journals, unpublished studies, conference proceedings, and cross-references were explored. 37 publications were included for quantitative synthesis, comprising 55 cases. The mean age of the patients was 59.56 years, and the lesions were more prevalent in males than in females. OAM's were most prevalent in the maxilla (67.2%) with ulceration, pinkish-red color, nodular mass, and pain. 2 patients (3.36%) were alive at their last follow-up, and 25 were dead (45.4%). Univariate survival analysis of clinical variables revealed that age older than 68 years (p = 0.003), mandibular gingiva (p = 0.007), round cells (p = 0.004), and surgical excision along with chemotherapy & radiation therapy (p = 0.001) were significantly associated with a lower survival rate. Oral Amelanotic Melanoma is a neoplasm with a poor prognosis, presenting a 6.25% possibility of survival after 5 years. Patients older than 68 years, lesions in the mandibular gingiva, round cells, and surgical excision along with chemotherapy and radiotherapy, presented the worst prognosis. However, they did not represent independent prognostic determinants for these patients.

Primary acral amelanotic melanoma: A rare case report

The aim of the present study was to present a rare case of primary acral amelanotic malignant melanoma (AMM). A 61-year-old man developed an aggressive tumor in the front part of the sole of his left foot, which continued to increase in size for >1 year. The biopsy results revealed epidermis loss, ulcer formation, and the presence of abundant allotropic tumor cells throughout the dermis, with deeply stained nuclei, light reddish cytoplasm and visible multinucleated giant cells with heterogeneous nuclear division. The tumor cells exhibited partial formation of nests and bundled distribution, and there were no observed pigment particles. The diagnosis was confirmed as AMM based on the findings of the histopathological examination and immunohistochemical staining for Ki67 (+++), Melan-A (+++), human melanoma black 45 (+), CD20 (-), cytokeratin (CK)7 (-) and CK5/6 (-).

Oral Amelanotic Melanomas: Clinicopathologic Features of 8 Cases and Review of the Literature

Mucosal melanomas are aggressive tumors, rarely observed in the oral cavity. The diagnosis is based on the clinical and microscopical features. Often these tumors had variable amounts of melanin pigmentation. However, when melanin is absent, the tumors are denominated amelanotic, presenting a tendency to misdiagnosis and delayed treatment. The aim of this study was to describe the clinicopathologic features of a series of oral amelanotic melanomas (OAM). Records of all cases of OAM were retrospectively retrieved from oral pathology services from January 2002 to January 2019. Data regarding the clinical features, morphological aspects, immunohistochemical reactions, treatment, and follow-up status were collected. Eight cases of OAM were included, 6 in men and 2 in women (ratio of 3:1) ranging in age from 33 to 77 years (mean 53.6 years). Clinically, the tumors presented as masses or ulcerated swellings. The most common intraoral locations of the tumors were gingiva and palate. Cervical lymph node metastasis was detected in 3 patients at the first examination. All but one patient died from complications of the tumors after a mean follow-up period of 8.5 months. In conclusion, OAM is a very aggressive malignant tumor, and when melanin is absent, an immunohistochemical panel comprising S100, melan A, HMB45, and SOX10 should be performed.

Rare and Extensive Malignant Melanoma of the Oral Cavity: Report of Two Cases

Primary oral melanomas are uncommon malignant neoplasm of melanocytes origin. The most common site of oral melanoma is maxillary gingiva and hard palate. Oral mucosal melanoma exhibit a pathobiological behavior and clinical features different from cutaneous melanomas. Oral melanomas are often clinically silent which may consequently result in delayed diagnosis; thus, making the prognosis extremely poor. This case report presents clinical, histopathological and immunohistochemical features of two cases of advanced oral melanoma, one pigmented or melanotic melanoma in a 46-year-old female and another amelanotic melanoma in a 59-year-old male patient, with chief complaint of swelling in oral mucosa. Most oral melanomas are usually asymptomatic lesions with quick growing. Thus, the most cases are detected in late stage of diagnosis. Early diagnosis with careful examination by dentists, and early biopsy of pigmented and suspicious non-pigmented lesions would have an imperative role in more survival rate and better prognosis.