Vascular Lesions of the Salivary Glands

Introduction

Vascular lesions may involve both major and minor salivary glands, simultaneously with other neck spaces. Most cases are present in pediatric patients. This chapter reviews the differential diagnosis and treatment of hemangiomas and vascular malformations ( Table 44.1 ).

Hemangiomas

A hemangioma is a congenital vascular tumor consisting of a proliferation of placenta-related capillaries. The term “hemangioma”, includes all types of hemangiomas, but mostly it refers to a rapidly growing benign vascular tumor; infantile hemangioma. They go through a rapid growing phase and greatly increase in volume; this is different from the capillary hemangioma, which occurs in adults. Hemangiomas are not always present at birth but can have a pink or purple pigmentation that can predict its pathogenesis. They usually become apparent in the early years after birth and increase in size in their first year of life. During the development phase, the endothelial cells multiply rapidly and become flat during the involution. Among mesenchymal salivary gland tumors, 50–60% consist of hemangiomas, and about 30% of pediatric salivary gland tumors are hemangioma. Infantile hemangioma is the most common tumor in childhood. In Asians, they are relatively rare, while in Caucasians, they are relatively common. About 80% of hemangiomas involving salivary glands occur in the parotid gland, 18% in the submandibular gland, and 2% in the minor salivary glands. After presentation, the hemangioma will continue to proliferate over the next 10–14 months, then undergo a variable involution phase, in which the lesion is softened and contracted. The lesion begins to regress naturally between the ages of 1 and 2. About half of patients experience a complete involution before the age of 5; 70% by age 7; and 90% by age 9 years. Vascular lesions of salivary glands can be confirmed by MRI in selected cases.

Specific treatment regimens need to be individualized. Historically, observation without intervention has been recommended, as the lesion disappears spontaneously. However, hemangioma can be disfiguring, and it can take years to involute. In many cases, residual fibrous fatty tissue, overlying stretched and scarred skin, and persistent mass malformation needs to be addressed. Intervention is warranted in selected cases.

Superficial lesions can be treated with a pulsed dye laser. However, it does not offer sufficient penetration to treat a hemangioma in the parotid gland. Pulsed dye laser (595 nm) is used as an adjunct therapy to treat the overlying superficial component of the lesion. Steroid therapy historically has been the main treatment of hemangioma. Systemic corticosteroid treatment has been shown to slow, and in many cases reverse, the growth of hemangiomas. Rebound growth is often seen after cessation of therapy. Intralesional steroid injection has been shown to be comparable with systemic therapy, reducing the potential systemic side effects. The therapeutic response can start 2–3 days after the injection and repeated injections can be considered every 8–12 weeks. Steroids are only effective in proliferative lesions. Other reported medical interventions for hemangiomas include vincristine and interferon.

β-blockers have now emerged as the drug of choice for hemangiomas. The inhibitory effect of β-blockers on proliferating hemangiomas has revolutionized the treatment of problematic hemangiomas of the head and neck. Recently, a topical agent, such as timolol, has also been reported to show successful outcomes in the treatment of superficial hemangioma, but there is still no long-term comparative study.

The decision on when to perform hemangioma surgery is controversial. Hemangiomas exhibit different growth rates, with many lesions resolving after a few months and others showing no change. Parents should be informed of this diversity and it is usually advisable to delay surgery until involution timing can be predicted. Frequently, enough of the hemangioma will involute to obviate the need for extensive surgery. If the hemangioma remains large at approximately 3–4 years of age, surgical removal can be offered for facial symmetry.

While the surgical steps are the same as a routine parotidectomy and submandibular gland resection, surgery for hemangioma involving salivary gland tissue can be difficult and frequently involves substantial blood loss and risk to the facial nerve. The facial nerve is frequently surrounded by hemangioma and dissection can be difficult due to the vascularity of the hemangioma infiltrating the parotid gland and the perineurium of the facial nerve, thus intraoperative facial nerve monitoring is a valuable tool. The purpose of the surgery is not to remove all hemangioma but to create symmetry and to remove bulk. Usually a superficial parotidectomy is sufficient to accomplish this goal, and further dissection of the nerve is unnecessary. In many cases, redundant scarred skin can be resected without formal identification of the facial nerve, as long as superficial planes are respected.