Frequent activating PIK3CA mutations in sporadic angiolipoma

METTL3 accelerates staphylococcal protein A (SpA)-induced osteomyelitis progression by regulating m6A methylation-modified miR-320a

Osteomyelitis (OM) is an inflammatory disease of bone infection and destruction characterized by dysregulation of bone homeostasis. Staphylococcus aureus (SA) has been reported to be the most common pathogen causing infectious OM. Recent studies have demonstrated that N6-methyladenosine (m6A) regulators are associated with the development of OM. However, the molecular mechanism of m6A modifications in OM remains unclear. Here, we investigated the function of methyltransferase-like 3 (METTL3)-mediated m6A modification in OM development. In this study, human bone mesenchymal stem cells (hBMSCs) were treated with staphylococcal protein A (SpA), a vital virulence factor of SA, to construct cell models of OM. Firstly, we found that METTL3 was upregulated in OM patients and SpA-induced hBMSCs, and SpA treatment suppressed osteogenic differentiation and induced oxidative stress and inflammatory injury in hBMSCs. Functional experiments showed that METTL3 knockdown alleviated the inhibition of osteogenic differentiation and the promotion of oxidative stress and inflammation in SpA-treated hBMSCs. Furthermore, METTL3-mediated m6A modification upregulated miR-320a expression by promoting pri-miR-320a maturation, and the mitigating effects of METTL3 knockdown on SpA-mediated osteogenic differentiation, oxidative stress and inflammatory responses can be reversed by miR-320 mimic. In addition, we demonstrated that phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) was a downstream target of miR-320a, upregulation of PIK3CA alleviated miR-320a-induced inhibition of osteogenic differentiation, and upregulation of oxidative stress and inflammatory responses during SpA infection. Finally, we found that silencing METTL3 alleviated OM development by regulating the miR-320a/PIK3CA axis. Taken together, our data demonstrated that the METTL3/m6A/miR-320a/PIK3CA axis regulated SpA-mediated osteogenic differentiation, oxidative stress, and inflammatory responses in OM, which may provide a new therapeutic strategy for OM patients.

A rare case report of infratentorial cisternal angiolipoma with review of literature

Angiolipomas are slow-growing benign mesenchymal-derived tumors consisting of mature adipocytes and thin-walled blood vessels. While the majority of angiolipomas are found in subcutaneous tissues, rarely there are case reports of intracranial lesions. We present a case of cisternal angiolipoma in a 10-year-old female. She presented with vague symptoms like dizziness without neurological deficits and radiological evaluation confirmed a left-sided infratentorial cisternal partially enhancing mass. She underwent craniotomy and had complete resection of the mass, which was histologically composed of mature adipocytes and blood vessels, consistent with angiolipoma. A review of the literature found only 18 cases of intracranial angiolipoma ever reported with our case representing the first case of infratentorial cisternal region.

Case Report: Giant Thyroid Angiolipoma-Challenging Clinical Diagnosis and Novel Genetic Alterations

BACKGROUND

A 64-year-old man presented with a 7.8 cm lipomatous thyroid mass discovered on magnetic resonance imaging.

METHODS

After two non-diagnostic fine needle aspirations (FNAs) were performed, computed tomography (CT) revealed features concerning for malignancy including central necrosis and infiltrative borders. A third FNA was still non-diagnostic. Total thyroidectomy was performed.

RESULTS

Upon pathologic examination, the final diagnosis was primary thyroid angiolipoma. The lesion contained central fat necrosis with ischemic features, attributable to the FNAs.

CONCLUSION

Ours is the third published case report of this rare entity. To date, no lipomatous thyroid tumor has undergone extensive genomic testing. Next-generation sequencing of our case revealed multiple genetic alterations, supporting the concept of angiolipomas being true neoplasms. Whereas the two previously reported cases in the literature were radiographically much smaller and appeared indolent, the large tumor in our case exhibited radiographic features concerning for liposarcoma, which belied the benign final pathologic diagnosis. Our case demonstrates that conservative surgical management (partial thyroidectomy) may be considered for lipomatous thyroid tumors, with further interventions to be determined only after final pathologic diagnosis.

Angiolipoma: a review of 778 lesions in 344 patients

BACKGROUND

Angiolipomas are benign subcutaneous nodules that are commonly multifocal and easily overlooked by those not familiar with their appearance. The objective of this study was to identify the spectrum of the clinical and imaging features of this lesion, to include MR, CT, and US features.

METHODS

A retrospective review of our institutional pathology database for biopsy-proven cases of angiolipoma between January 1, 2019, through December 31, 2021, was done. We identified 334 patients who underwent surgical resection of 788 individual lesions. MR imaging studies were available in 43 cases, CT in 39 cases, and ultrasound imaging in 72 cases. Clinical features (patient age, gender, surgical indication, number of lesions) were reviewed. Imaging feature analysis included the anatomic location, content of fat, vascularity, and modality-specific imaging features.

RESULTS

All 778 angiolipomas were located in the subcutaneous tissues (median size, 2.4 cm, range 0.4-7.7 cm), with over 51% located in the upper extremity. The most common presentation was a symptomatic mass or slowly growing symptomatic mass. Imaging showed a subcutaneous lesion with a lobulated bean shape, which typically abutted the skin. Intralesional fat was identified in 85% of lesions on CT and MRI. Vessels were commonly seen on CT and MR, with enhancement best seen on MR. On US, lesions were heterogeneous and mildly hyperechoic, most often with no identifiable vascularity.

CONCLUSION

Angiolipomas typically have characteristic imaging features. Awareness of this diagnosis and the spectrum of its imaging features is important and can facilitate a definitive diagnosis.

Recurrent driver mutations in benign tumors

The understanding of the molecular pathogenesis of benign tumors may bring essential information to clarify the process of tumorigenesis, and ultimately improve the understanding of events such as malignant transformation. The definition of benign neoplasia is not always straightforward and herein the issues surrounding this concept are discussed. Benign neoplasms share all cancer hallmarks with malignancies, except for metastatic potential. Recently, next-generation sequencing has provided unprecedented opportunities to unravel the genetic basis of benign neoplasms and, so far, we have learned that benign neoplasms are indeed characterized by the presence of genetic mutations, including genes rearrangements. Driver mutations in advanced cancer are those that confer growth advantage, and which have been positively selected during cancer evolution. Herein, some discussion will be brought about this concept in the context of cancer prevention, involving precursor lesions and benign neoplasms. When considering early detection and cancer prevention, a driver mutation should not only be advantageous (i.e., confer survival advantage), but predisposing (i.e., promoting a cancer phenotype). By including the benign counterparts of malignant neoplasms in tumor biology studies, it is possible to evaluate the risk posed by a given mutation and to differentiate advantageous from predisposing mutations, further refining the concept of driver mutations. Therefore, the study of benign neoplasms should be encouraged because it provides valuable information on tumorigenesis central for understanding the progression from initiation to malignant transformation.