Background Head and neck mucosal melanomas (MMs) are rare tumors with adverse outcomes and poorer prognoses than their more common cutaneous counterparts (cutaneous melanomas—CMs). Few studies have compared the expression of mitochondrial dynamic markers in these tumors. This study aimed to assess the correlations of mitochondrial markers with melanoma progression and their potential as predictors of lymph node involvement and distant metastasis. Methods Immunohistochemistry against anti‐mitochondrial (AMT), dynamin‐related protein 1 (DRP1), mitochondrial fission protein 1 (FIS1), mitofusin‐1 (MFN1), and mitofusin‐2 (MFN2) antibodies was performed in 112 cases of head and neck CM and MM. A Cox regression multivariate model was used to assess the correlation of AMT, FIS1, and MFN2 expressions considering the risk for nodal and distant metastasis. Results All markers studied presented higher staining in tumor cells than normal adjacent tissues. Higher mitochondrial content was observed in MM than in CM, and it was significantly associated with nodal metastasis in oral melanomas. Both FIS1 and DRP1 expressions were related to advanced Clark's levels in CM, and they were overexpressed in oral melanomas. Moreover, increased immunoexpression of MFN2 was significantly associated with a higher risk of metastasis in CM, and it was also overexpressed in sinonasal melanomas. Conclusions Our results suggest that mitochondrial fission and fusion processes can play an important role during multiple stages of tumorigenesis and the development of nodal and distant metastasis in cutaneous and mucosal melanomas.

Objective This living systematic review aims to integrate the morphological and tissue-based molecular characterization of oral lesions occurring in individuals infected by COVID-19 (OLICs). Materials and Design This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Web of Science, Scopus, Ovid, Embase, and LILACS were searched to identify reports on OLICs with morphological and/or tissue-based molecular data. Results Four studies reporting five cases were included. Three patients were male, and the mean age of the individuals was 47.6 years. The most reported anatomical location was the palate (n = 4), whereas ulcers were the most frequent clinical presentation (n = 3). Histopathologically, all cases revealed cell vacuolization and exocytosis in the epithelial layer. In the mesenchymal layer, inflammatory cell infiltrate and thrombi/microvascular thrombosis were observed in three cases. Immunohistochemical reactions were performed in two cases. Both cases were negative for HHV-1, HHV-2, and CMV. One case revealed positivity for SARS-CoV-2 spike protein. No other molecular tests were found for the characterization of OLIC. Conclusions The pathological characteristics of OLICs are still unspecific. However, with the ongoing COVID-19 pandemic and well-documented new cases, whether OLICs are due to coinfections or has a primary origin can be determined.

No abstract

Background: Oral focal mucinosis (OFM) is a rare benign condition of unknown etiology, considered the oral counterpart of cutaneous focal mucinosis. We report the clinicopathologic features of 21 cases of OFM in conjunction with a review of the literature. Methods: Clinical data were collected from the records of five oral and maxillofacial pathology services. All cases were evaluated by hematoxylin and eosin staining, histochemistry, and immunohistochemistry (vimentin, S-100, α-SMA, CD34, and mast cell). Results: The series comprised 14 females (66.7%) and seven males (33.3%), with a mean age of 48.2 ± 20.7 years (range: 8-77 years) and a 2:1 female-to-male ratio. Most of the lesions affected the gingiva (n = 6, 28.6%) and presented clinically as asymptomatic sessile or pedunculated nodules with fibrous or hyperplasic appearance. All cases were negative for S-100 protein, CD34, and α-SMA and positive for Alcian blue staining. Conservative surgical excision was the treatment in all cases, and there was only one recurrence. Conclusion: OFM is a rare benign disorder that is often clinically misdiagnosed as reactive lesions or benign proliferative processes. Dermatologists and pathologists should consider OFM in the differential diagnosis of soft tissue lesions in the oral cavity, mainly located in the gingiva. K E Y W O R D S connective tissue diseases, diagnosis, oral focal mucinosis, oral pathology 1 | INTRODUCTION Oral focal mucinosis (OFM) is considered to be the oral counterpart of cutaneous focal mucinosis (CFM) that likely develops due to an overproduction of hyaluronic acid by fibroblasts. 1-3 As a result, a well-demarcated myxomatous tissue positive for Alcian blue (pH 2.5) is observed microscopically; which may mimic other oral myxoid lesions, such as soft-tissue myxoma, fibrous hyperplasia with myxoid degeneration, nerve sheath myxoma (NSM), myxoid neurofibroma, and mucocele. 1

No abstract

Salivary gland tumors (SGT) represent an uncommon heterogeneous group of tumors with complex clinical and pathological characteristics. The prevalence of these lesions varies between studies but has been estimated between 3 and 6% of all tumors in the head and neck region. The present study aimed to evaluate the distribution and demographic findings of salivary gland tumors diagnosed in an oral pathology service in Mexico. A retrospective descriptive cross-sectional study was performed. A total of 164 cases of SGT from a private oral pathology service were diagnosed between 2000 and 2019 in Mexico City. All cases were reviewed histologically, and demographic data and histopathological diagnoses were collected. A total of 110 (67.1%) tumors were benign, and 54 (32.9%) were malignant. The majority of patients were female (n = 100, 61.0%) with an overall female:male ratio of 1.6:1. The minor salivary glands were affected more than the major salivary glands (68.9% vs. 25.6%). The palate (n = 67, 40.9%) was the most commonly affected site, followed by the parotid gland (n = 37, 22.6%), lips (n = 16, 9.8%), and buccal mucosa (n = 14, 8.5%). Pleomorphic adenoma (n = 88; 80.0%) and mucoepidermoid carcinoma (n = 16, 29.6%) were the most frequent benign and malignant tumors, respectively. The general features of SGT from the studied Mexican population shared some similarities and differences compared to previously reported series from various parts of the world.

No abstract

The start angle of combustion plays an important role in determining the performance and the exhaust emissions of a diesel engine. In this paper, the assessment of the behavior of a marine diesel engine is presented for twelve start angles of combustion. The simulation is done using a 1D engine simulation code developed and implemented in Matlab, which was validated with a commercial software tool. Three engine speeds are considered during the simulation. The optimum range of crank angles to start the combustion is determined for engine optimization. The heat release rate and the Wiebe function are used to determine the behavior of the combustion process. The amount of carbon dioxide (CO 2 ) and nitrogen oxide (NO x ) emissions are calculated for the different cases assumed. The simulation results are compared with data taken from a real engine.