Accumulating reports suggest that human glioblastoma contains glioma stem-like cells (GSCs) which act as key determinants driving tumor growth, angiogenesis, and contributing to therapeutic resistance. The proliferative signals involved in GSC proliferation and progression remain unclear. Using GSC lines derived from human glioblastoma specimens with different proliferative index and stemness marker expression, we assessed the hypothesis that sphingosine-1-phosphate (S1P) affects the proliferative and stemness properties of GSCs. The results of metabolic studies demonstrated that GSCs rapidly consume newly synthesized ceramide, and export S1P in the extracellular environment, both processes being enhanced in the cells exhibiting high proliferative index and stemness markers. Extracellular S1P levels reached nM concentrations in response to increased extracellular sphingosine. In addition, the presence of EGF and bFGF potentiated the constitutive capacity of GSCs to rapidly secrete newly synthesized S1P, suggesting that cooperation between S1P and these growth factors is of central importance in the maintenance and proliferation of GSCs. We also report for the first time that S1P is able to act as a proliferative and pro-stemness autocrine factor for GSCs, promoting both their cell cycle progression and stemness phenotypic profile. These results suggest for the first time that the GSC population is critically modulated by microenvironmental S1P, this bioactive lipid acting as an autocrine signal to maintain a pro-stemness environment and favoring GSC proliferation, survival and stem properties.

We described a large PJP cluster among HTx recipients, supporting the nosocomial acquisition of PJP through interhuman transmission. Based on this experience, extended prophylaxis for more than 6 months after HTx could be considered in specific settings. Further work is required to understand its optimal duration and timing based on individual risk factor profiles and to define standardized countermeasures to prevent and limit PJP outbreaks.

Sclerosing polycystic adenoma (SPA) is a rare salivary gland neoplasm originally thought to represent a non-neoplastic lesion. Recently we have encountered an index case of apocrine intraductal carcinoma of parotid gland of 62-year-old man with invasive salivary duct carcinoma component arising from SPA, a combination of tumor entities that has never been published so far. Here, we further explore the nature of SPA by evaluating 36 cases that were identified from the authors’ consultation files. The patients were 25 females and 11 males aged 11 to 79 years (mean, 47.8 y). All tumors originated from the parotid gland. Their size ranged from 11 to 70 mm (mean, 28 mm). Histologically, all cases revealed characteristic features of SPA, such as lobulated well-circumscribed growth, focal hyalinized sclerosis, presence of large acinar cells with abundant brightly eosinophilic intracytoplasmic granules, and ductal components with variable cytomorphologic characteristics, including foamy, vacuolated, apocrine, mucous, clear/ballooned, squamous, columnar and oncocyte-like cells. In all cases, there were foci of intraluminal solid and cribriform intercalated duct-like epithelial proliferations with variable dysplasia which were positive for S100 protein and SOX10, and fully enveloped by an intact layer of myoepithelial cells. In addition, 14/36 cases (39%) had focal intraductal cribriform and micropapillary apocrine-type dysplastic epithelial structures composed of cells positive for androgen receptors and negative for S100/SOX10. The intraductal proliferations of both types showed focal mild to severe dysplasia in 17 cases (17/36; 47%). Two cases showed overt malignant morphology ranging from high-grade intraductal carcinoma to invasive carcinoma with an apocrine ductal phenotype. Next generation sequencing using ArcherDX panel targeting RNA of 36 pan-cancer-related genes and/or a TruSight Oncology 170/500 Kit targeting a selection of DNA from 523 genes and RNA from 55 genes was performed. Tumor tissue was available for molecular analysis in 11 cases, and 9 (9/11; 82%) of them harbored genetic alterations in the PI3K pathway. Targeted sequencing revealed HRAS mutations c.37G>C, p.(Gly13Arg) (2 cases) and c.182A>G, p.(Gln61Arg) (2 cases), and PIK3CA mutations c.3140A>G, p.(His1047Arg) (3 cases), c.1633G>A, p.(Glu545Lys) (1 case), and c.1624G>A, p.(Glu542Lys) (1 case). Moreover, mutations in AKT1 c.49G>A, p.(Glu17Lys) and c.51dup, p.(Tyr18ValfsTer15); c.49_50delinsAG, p.(Glu17Arg) (as a double hit) were found (2 cases). In addition, germinal and somatic mutation of PTEN c.1003C>T, p.(Arg335Ter); c.445C>T, p.(Gln149Ter), respectively, were detected. Gene fusions were absent in all cases. These prevalent molecular alterations converging on one major cancer-related pathway support the notion that SPA is a true neoplasm with a significant potential to develop intraluminal epithelial proliferation with apocrine and/or intercalated duct-like phenotype. The name SPA more correctly reflects the true neoplastic nature of this enigmatic lesion.

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Summary The World Health Organization’s (WHO) updated classification of head and neck tumors (2017) defined odontogenic fibroma as a rare neoplasm. In this report, we describe an unusual, typical and rare variant of a central odontogenic fibroma with diffuse amyloid-like protein stromal deposition, and discuss the differential diagnosis with other entities. Radiographically, this lesion presented as a well-defined radiolucency of the mandible, partially cystic. Histologically, the lesion showed a unique confluence of odontogenic epithelial rests in a moderately cellular connective tissue. Immunohistochemical staining highlighted a mixture of benign epithelial and Langerhans cells within connective tissue with diffuse amyloid-like stromal deposition. The importance of recognizing this variant of odontogenic fibroma is due to its benign prognosis and clinical course.