Tufted angioma with associated Kasabach-Merritt phenomenon caused by somatic mutation in GNA14

Congenital Vascular and Lymphatic Diseases

Over the past several centuries, the integration of contemporary medical techniques and innovative technologies, like genetic sequencing, have played a pivotal role in enhancing our comprehension of congenital vascular and lymphatic disorders. Nonetheless, the uncommon and complex characteristics of these disorders, especially considering their formation during the intrauterine stage, present significant obstacles in diagnosis and treatment. Here, we review the intricacies of these congenital abnormalities, offering an in-depth examination of key diagnostic approaches, genetic factors, and therapeutic methods.

Cutaneous vascular tumors: an updated review

Cutaneous vascular tumors constitute a heterogeneous group of entities that share overlapping morphologic and immunohistochemical features, which can be diagnostically challenging for pathologists and dermatopathologists. Our understanding and knowledge of vascular neoplasms have improved over time, resulting in both a refinement of their classification by the International Society for the Study of Vascular Anomalies (ISSVA) and an improvement in the accurate diagnosis and clinical management of vascular neoplasms. This review article aims to summarize the updated clinical, histopathological, and immunohistochemical characteristics of cutaneous vascular tumors, as well as to highlight their associated genetic mutations. Such entities include infantile hemangioma, congenital hemangioma, tufted angioma, spindle cell hemangioma, epithelioid hemangioma, pyogenic granuloma, Kaposiform hemangioendothelioma, retiform hemangioendothelioma, pseudomyogenic hemangioendothelioma, Kaposi sarcoma, angiosarcoma, and epithelioid hemangioendothelioma.

Case Report: Kaposiform hemangioendothelioma with PIK3CA mutation successfully treated with sirolimus

Kaposiform hemangioendothelioma (KHE) is an extremely rare, locally aggressive vascular neoplasm. The etiopathogenesis of KHE is still poorly understood. In the present study, we found a new mutation in KHE (c.685delA, p.Thr229fs). The KHE patient with the PIK3CA mutation showed complete regression after sirolimus treatment. We propose that the presence of the PIK3CA mutation in KHE may correlate with good response to sirolimus.

Benign and low-grade superficial endothelial cell neoplasms in the molecular era

Vascular tumors are the most common mesenchymal neoplasms of the skin and subcutis, and they encompass a heterogeneous group with diverse clinical, histological, and molecular features, as well as biological behavior. Over the past two decades, molecular studies have enabled the identification of pathogenic recurrent genetic alterations that can be used as additional data points to support the correct classification of these lesions. The purpose of this review is to summarize the available data related to superficially located benign and low-grade vascular neoplasms and to highlight recent molecular advances with the role of surrogate immunohistochemistry to target pathogenic proteins as diagnostic biomarkers.

MEK inhibition reduced vascular tumor growth and coagulopathy in a mouse model with hyperactive GNAQ

Activating non-inherited mutations in the guanine nucleotide-binding protein G(q) subunit alpha (GNAQ) gene family have been identified in childhood vascular tumors. Patients experience extensive disfigurement, chronic pain and severe complications including a potentially lethal coagulopathy termed Kasabach-Merritt phenomenon. Animal models for this class of vascular tumors do not exist. This has severely hindered the discovery of the molecular consequences of GNAQ mutations in the vasculature and, in turn, the preclinical development of effective targeted therapies. Here we report a mouse model expressing hyperactive mutant GNAQ in endothelial cells. Mutant mice develop vascular and coagulopathy phenotypes similar to those seen in patients. Mechanistically, by transcriptomic analysis we demonstrate increased mitogen activated protein kinase signaling in the mutant endothelial cells. Targeting of this pathway with Trametinib suppresses the tumor growth by reducing vascular cell proliferation and permeability. Trametinib also prevents the development of coagulopathy and improves mouse survival.

Cerebral Tufted Angioma with Gradually Developing Peritumoral Edema: A Case Report

Tufted angioma is a benign vascular tumor in which immature endothelial and pericyte cells and lymphatic vascular endothelium grow. It manifests as a flat, painful erythema that gradually expands mainly on the trunk and extremities. Although tufted angiomas can also occur in other areas of the body and may be more locally invasive, they rarely occur intracranially. A 63-year-old man underwent magnetic resonance imaging (MRI) for a brain check-up 8 years before his visit to our institute, which detected a mass lesion with surrounding cerebral edema in the left frontal lobe. The patient was followed up with annual MRI analysis, which indicated slow tumor growth and gradual development of peritumoral edema. The tumor was treated by gross-total resection. Histological analysis showed a slightly dilated microvascular core surrounded by many capillary aggregates in the brain parenchyma. Immunohistochemical findings indicated that the vascular endothelial cells were positive for CD34 and Brahma-related gene-1 and were surrounded by smooth muscle actin-positive pericytes. These findings were consistent with tufted angioma. Intracranial tufted angioma is uncommon, but it should be considered in the differential diagnosis for intracranial tumorous lesions. Long-term follow-up is necessary to unravel the natural history of the disease.

ISSVA Classification of Vascular Anomalies and Molecular Biology

Vascular anomalies include various diseases, which are classified into two types according to the International Society for the Study of Vascular Anomalies (ISSVA) classification: vascular tumors with proliferative changes of endothelial cells, and vascular malformations primarily consisting of structural vascular abnormalities. The most recent ISSVA classifications, published in 2018, detail the causative genes involved in many lesions. Here, we summarize the latest findings on genetic abnormalities, with the presentation of the molecular pathology of vascular anomalies.