Salivary glands are essential organs that produce and secrete saliva to the oral cavity. During gland morphogenesis, many developmental processes involve a series of coordinated movements and reciprocal interactions between the epithelium and mesenchyme that generate the ductal system and the secretory units. Recent studies have shown new findings about salivary gland development, particularly regarding lumen formation and expansion, with the involvement of apoptosis and cell polarization, respectively. Moreover, it has been observed that human minor salivary glands start forming earlier than previously published and that distinct apoptotic mediators can trigger duct lumen opening in humans. This review summarizes updated morphological and cellular features of human salivary glands and also explores new aspects of the human developmental process. Anat Rec, 300:1180-1188, 2017. © 2017 Wiley Periodicals, Inc.

Head and neck mucosal melanoma (MM) is an aggressive and rare neoplasm of melanocytic origin. To date, few retrospective series and case reports have been reported on MM. This article reviews the current evidence on head and neck MM and the molecular pathways that mediate the pathogenesis of this disease. Head and neck MM accounts for 0.7%-3.8% of all melanomas and involve (in decreasing order of frequency) the sinonasal cavity, oral cavity, pharynx, larynx, and upper esophagus. Although many studies have examined MM of the head and neck and the underlying molecular pathways, individual genetic and molecular alterations were less investigated. Further studies are needed to complement existing data and to increase our understanding of melanocytes tumorigenesis.

a diffuse expression in mucous and serous acini, in addition to strong apical membrane expression within lumen of intercalated ductal cells. This topographic analysis of AQP1, 3 and 5 revealed differences in the expression pattern throughout salivary gland developmental stages, suggesting different roles for each protein in human glandular maturation.

Oral mucosal melanoma is rare. Its incidence peaks between 41 and 60 years of age; male/female ratio is 2:1. Preferred oral sites include hard palate and maxillary gingiva. Risk factors have not been clearly identified, but pigmented lesions may be present before the diagnosis of oral melanoma. We report an unusual case of oral mucosal melanoma of long-standing duration on hard palate and maxillary alveolar ridge in a male patient. Histopathologic features confirmed the diagnosis of invasive melanoma with a prominent in situ component. A cell lineage derived from the tumor was established and characterized, with phenotypic markers of melanocytes.

Primary oral mucosal melanoma is an extremely rare and aggressive tumor arising from melanocytes located in the mucosal epithelium of the oral cavity. Although malignant melanoma of oral mucosa shares some clinical features with its cutaneous counterpart, it has been associated with a worst prognosis; its etiopathogenesis are still only partially unraveled as there is no influence of UV radiation. It is known that the mitogen-activated protein kinase pathway mediates cellular responses to growth signals and its activation is an important phenomenon in melanoma. The aim of this study was to evaluate NRAS and BRAF genes, both components of mitogen-activated protein kinase molecular pathway, and compare with their protein expression. Point mutations of NRAS (codons 12, 13, and 61) and BRAF (codon 600) were screened by pyrosequencing method, and its results were associated to the protein expression of RAS and BRAF performed by immunohistochemistry. The authors observed mutation in BRAF 600 (3/14), NRAS codons 12 and 13 (2/14), and NRAS codon 61 (2/8). One case showed positive RAS protein expression, but no mutation was observed. Twelve in 14 cases showed positive BRAF protein expression: 3 cases showed BRAF mutation; 2 cases showed NRAS codon 61 mutation; 2 cases showed NRAS codons 12 and 13 mutation but not simultaneously. Although NRAS and BRAF mutation frequency and RAS protein expression are low, BRAF protein expression was intense; probably, NRAS and BRAF mutations are independent events and alternative molecular mechanisms in the primary oral mucosal melanoma tumorigenesis.

Background: Detection of somatic mutations is a mandatory practice for therapeutic definition in precision oncology. However, somatic mutation detection protocols use DNA from formalin-fixed and paraffin-embedded (FFPE) tumor tissues, which can result in detection of nonreproducible sequence artifacts, especially C:G > T:A transitions, in DNA. In recent studies, DNA pretreatment with uracil DNA glycosylase (UDG), an enzyme involved in base excision repair, significantly reduced the number of DNA artifacts after mutation detection by next-generation sequencing (NGS) and other methods, without affecting the capacity to detect real mutations. This study aimed to evaluate the effects of UDG enzymatic pretreatment in reducing the number of DNA sequencing artifacts from FFPE tumor samples, to improve the accuracy of genetic testing in the molecular diagnostic routine. Methods: We selected 12 FFPE tumor samples (10 melanoma, 1 lung, and 1 colorectal tumor sample) with different storage times. We compared sequencing results of a 16-hotspot gene panel of NGS libraries prepared with UDG-treated and untreated samples. Results: All UDG-treated samples showed large reductions in the total number of transitions (medium reduction of 80%) and the transition/transversion ratio (medium reduction of 75%). In addition, most sequence artifacts presented a low variant allele frequency (VAF < 10%) which are eliminated with UDG treatment. Conclusion: Including UDG enzymatic treatment before multiplex amplification in the NGS workflow significantly decreased the number of artifactual variants detected in FFPE samples. Thus, including this additional step in the current methodology should improve the rate of true mutation detection in the molecular diagnostic routine.

The etiology and pathogenesis of oral mucosal melanomas are poorly understood, and no intraoral risk factors have been identified. Recent studies have postulated that DNA repair mechanisms and cell growth pathways are involved in the development of melanoma-particularly changes in the CDKN2A (p16-cyclinD-Cdk-pRb) and MAPK pathways (RAS, BRAF, MEK 1/2, and ERK 1/2 proteins). We examined the central components of the CDKN2A and RAS-RAF-MEK-ERK cascades by immunohistochemistry in a series of 35 primary oral melanomas by tissue microarray (TMA). We noted altered expression of the CDKN2A cascade proteins, although these modulations did not correlate significantly with clinical and pathological parameters. The expression of MAP kinase cascade proteins changed in most cases. We observed that 28.57% of cases were RAS-positive and that 82.85% and 74.28% of cases were positive for BRAF and ERK2, respectively; MEK2 and ERK1 were not expressed in 48.57% and 80% of cases, and all cases were negative for MEK1. The absence of RAS and ERK1 and positivity for BRAF and ERK2 were associated with higher histological grade, vascular invasion, and metastasis. Expression of MEK2 was significantly linked to vascular invasion (P = 0.043). The CDKN2A and MAPK pathways require further study in mucosal melanomas, but our results highlight the significance of important alterations, particularly with regard to histological indicators of poor prognosis in primary oral mucosal melanomas, independent of UV exposure.

FUNDAMENTOS: A deleção e mutação do gene CDKN2a que codifica um inibidor específico da ciclina dependente de quinase 4, a proteína p16, têm sido implicadas na tumorigênese do melanoma cutâneo. Entretanto, pouco se conhece sobre essas alterações genéticas em melanomas de mucosa oral. OBJETIVOS: Verificar a presença de alterações no gene p16 e sua expressão protéica em melanomas esporádicos orais e cutâneos. MATERIAL E MÉTODOS: Avaliaram-se 36 espécimes de melanoma primário (sete orais e 29 cutâneos). Analisaram-se três exons do gene p16, pela técnica da reação em cadeia da polimerase/polimorfismo conformacional de fita simples do DNA.Verificou-se a expressão tecidual de proteína p16 por técnica imuno-histoquímica. Relacionaram-se os resultados com a espessura dos melanomas cutâneos. RESULTADOS: Cinco dos sete melanomas orais e 17 dos 29 melanomas cutâneos apresentaram indício de alteração no gene p16. Alterações do exon 2 foram as mais freqüentes, sendo 19 casos nos produtos obtidos com o mesmo iniciador. Observou-se expressão tecidual de p16 em apenas um melanoma oral, em 10/13 (76,9%) casos de melanoma cutâneo de espessura até 1mm e em sete de oito (87,5%) casos de espessura superior a 1mm. CONCLUSÃO: A freqüência de indícios de alteração na análise genética de p16 nos melanomas de mucosa oral foi de 71,42% e de 58,6% nos cutâneos. É possível sugerir a participação de alterações do gene p16 na patogenia do melanoma esporádico de mucosa oral. Não houve relação da sugestão de alteração genética do gene p16 e de sua expressão tecidual com a espessura dos melanomas cutâneos de diferentes subtipos histológicos.