Malignant Superficial Mesenchymal Tumors in Children

SIMPLE SUMMARY: Malignant tumors of the skin and subcutaneous tissue are rare in children. Most of these cancers are mesenchymal tumors and among these tumors, most have an intermediate malignant potential or are considered low grade sarcomas. In addition, some sarcomas of deep soft tissues may also involve the skin by contiguity. This review aims to sort out the diversity of these malignant mesenchymal tumors in children, with a particular focus on clinical features that may be useful for clinicians (especially age at presentation) and on the newest entities and genetic data. ABSTRACT: Malignant superficial mesenchymal tumors are a very diverse group of neoplasms with few clinical and radiological discriminatory factors. Hence, some of these cancers are rarely suspected based on clinical and radiological grounds, others may be easily misdiagnosed, and the histological analysis of a biopsy or resection is central in the diagnostic process. In children, the age at presentation is a major element of the differential diagnosis. Some tumors have a very distinct epidemiology, while others may be seen at any age. More recently, the advances in molecular biology have greatly improved the diagnosis of mesenchymal tumors and new entities are still being described. In the present review, we provide an overview of the diversity of malignant superficial mesenchymal tumors in children, including new and/or rare entities. We discuss the important diagnostic features, be they clinical, histological, or molecular. Special attention was given to the genetic features of these tumors, particularly when they were helpful for the diagnosis or treatment.