Carotid Body Tumor Microenvironment

Single-cell transcriptome analysis reveals tumoral microenvironment heterogenicity and hypervascularization in human carotid body tumor

Carotid body tumor (CBT) is a rare neck tumor located at the adventitia of the common carotid artery bifurcation. The prominent pathological features of CBT are high vascularization and abnormal proliferation. However, single-cell transcriptome analysis of the microenvironment composition and molecular complexity in CBT has yet to be performed. In this study, we performed single-cell RNA sequencing (scRNA-seq) analysis on human CBT to define the cells that contribute to hypervascularization and chronic hyperplasia. Unbiased clustering analysis of transcriptional profiles identified 16 distinct cell populations including endothelial cells (ECs), smooth muscle cells (SMCs), neuron cells, macrophage cells, neutrophil cells, and T cells. Within the ECs population, we defined subsets with angiogenic capacity plus clear signs of later endothelial progenitor cells (EPCs) to normal ECs. Two populations of macrophages were detectable in CBT, macrophage1 showed enrichment in hypoxia-inducible factor-1 (HIF-1) and as well as an early EPCs cell-like population expressing CD14 and vascular endothelial growth factor. In addition to HIF-1-related transcriptional protein expression, macrophages1 also display a neovasculogenesis-promoting phenotype. SMCs included three populations showing platelet-derived growth factor receptor beta and vimentin expression, indicative of a cancer-associated fibroblast phenotype. Finally, we identified three types of neuronal cells, including chief cells and sustentacular cells, and elucidated their distinct roles in the pathogenesis of CBT and abnormal proliferation of tumors. Overall, our study provided the first comprehensive characterization of the transcriptional landscape of CBT at scRNA-seq profiles, providing novel insights into the mechanisms underlying its formation.

Microsurgery in carotid body paraganglioma

Objectives

In carotid paraganglioma surgery, magnification is crucial to properly evaluate the anatomical relationships between mass, carotid wall, cranial nerves, tumour vascular supply and fascial envelope. The aims of this study are to describe the microsurgical technique, along with the underlying microsurgical anatomy, and to assess outcomes in terms of disease control, complications and functional results.

Methods

Twenty-six patients, accounting for 29 carotid paragangliomas, treated with microsurgery by the same senior surgeon over a 35-year period, were included.

Results

No carotid injury requiring repair, nor peri- or post-operative stroke occurred in this series. No surgical injury of the main trunk of VII to XII cranial nerves occurred. Complete excision was obtained in all cases and no recurrence was observed during follow-up.

Conclusions

The small study size and its retrospective nature suggests caution; however, our results show that microsurgery can allow a safe and precise dissection of the carotids and nerves.

Carotid body tumors: A retrospective case series of 11 patients

BACKGROUND

Carotid body tumors (CBTs) are uncommon neuroendocrine tumors located near the carotid bifurcation within the carotid body. CBTs are slow-growing; affected individuals may remain asymptomatic for years and are often diagnosed incidentally following imaging studies. When present, symptoms are nonspecific. Because incidence is low, retrospective review of CBT case series is an ideal study design for investigating common symptomology, identifying successful diagnostic tools, and evaluating treatment outcomes.

METHODS

This article describes a case series of 11 patients treated for CBTs at an academic medical center in the Southeastern US. A retrospective chart review of 11 patients who had been discharged from the hospital following treatment for CBTs between 2017 and 2021 was conducted. Descriptive statistics were used to delineate the case series.

RESULTS

There were four males (36%) and seven females (64%) included in the retrospective case series. The age range was 34 to 79 with a mean of 56.73 (standard deviation 16.038). Three patients were found to have a neck mass on physical exam. Additional symptoms included vocal cord paralysis, facial paralysis, ischemic stroke, Bell palsy, dysphonia, and dizziness. Two patients had familial CBTs. Ten patients underwent surgical excision.

CONCLUSION

This case series showed that patients with CBTs should be assessed with a combination of history and physical exams along with imaging studies to confirm the diagnosis. Because CBTs may become malignant and metastasize, it is important for NPs to be knowledgeable about presenting symptoms and appropriate diagnostic studies to be able to refer patients to vascular surgeons early to prevent complications.