Introduction

Why are benign soft tissue lesions important to pediatric surgeons?

Soft tissue masses in children are common heterogeneous lesions which include inflammatory, reactive, benign and malignant tumors. Most pediatric soft tissue masses are benign. It has been estimated that after excluding small benign cutaneous and subcutaneous lesions, approximately 75% of the soft tissue masses which require imaging are benign [1][2]. It is still very important to be able to differentiate benign processes from malignant ones as the speed with which workups occur might differ. In addition, the fact that some of these lesions occur rarely make it important for the pediatric surgeon to be able to diagnose these lesions based on clinical presentation and imaging modalities. If a definitive diagnosis cannot be made with noninvasive means, then one should proceed urgently to biopsy - whether it be imaged guided, incisional or excisional.

Vascular anomaliescomprise a large group of lesions that are classified by the International Society for the Study of Vascular anomalies [1]. There is a distinction between vascular malformations and vascular tumors. Vascular malformations result from localized defects in the development of blood vessels and the resultant masses grow with the child. They are usually present at birth and can be simple or combined. Vascular tumors, on the other hand, can occur after birth and may be benign (e.g. infantile hemangioma) or malignant (e.g. epithelioid hemangioendothelioma) [2]. Pyogenic granulomas are actually a type of vascular tumor, better known as a lobular capillary hemangioma.[3]

This topic will focus on nonvascular benign soft tissue lesions in the pediatric population.

Which aspects of benign soft tissue lesions present challenges for the pediatric surgeon?

There are many different types of benign soft tissue lesions. While dermoid cysts, epidermal inclusion cysts, ganglion cysts and pilomatrixoma are commonly encountered by the pediatric surgeon and have clinic characteristics that make their diagnosis straightforward, other soft tissue lesions are more difficult to treat. For example many different types of benign masses originate from fibrous, muscular and adipose tissue. Some of these lesions are congenital while others are acquired. They present similarly, grow slowly, occur infrequently, have many histologic subtleties and have nonspecific imaging characteristics. In addition, the nomenclature for these tumors is a moving target. For example, glomus tumor is now being classified as a vascular lesion. As new histologies are identified, new names are being added to the classification of benign soft tissue masses.

While these lesions may be histologically benign, many are prone to local recurrence. Therefore, even after complete excision, families need to understand the importance of follow-up. This can sometimes be difficult to convey and patients may return with large recurrences that are difficult to manage.