The most common symptoms of SVCS in children are similar to those in adults and include coughing, hoarseness, dyspnea, orthopnea, and chest pain. Symptoms that are less common but more serious are anxiety, confusion, lethargy, headache, distorted vision, a sense of fullness in the ears, and, especially, syncope.
SVCS is rare in children and appears at presentation in 12% of pediatric patients with malignant mediastinal tumors.[28,29] The etiology, diagnosis, and treatment of SVCS in children differs from that in adults. Whereas the most frequent cause of SVCS in adults is bronchogenic carcinoma, in children the most frequent malignant cause of the syndrome is non-Hodgkin lymphoma. As in adults, a frequent nonmalignant cause is thrombosis from catheterization for venous access.
A physical examination, chest radiograph, and the medical history of the patient are usually sufficient to establish a diagnosis of SVCS. If lymphoma or other malignant disease is suspected, it is desirable to obtain a tissue sample for diagnosis. However, the procedure to obtain the specimen may involve significant risk and may not be clinically feasible. Children with SVCS have a poor tolerance for the necessary general anesthesia because the accompanying cardiovascular and pulmonary changes aggravate the SVCS, often making intubation impossible. Also, extubation may be difficult or impossible, thus requiring prolonged airway provision (intubation). A CT scan of the chest to determine tracheal size, upright and supine echocardiography, and a flow volume loop may help evaluate anesthetic risk. Because anesthesia use is a serious risk, the diagnosis should be made with the least invasive means possible. Published reports suggest a stepwise approach to diagnosis.
When a malignant mass is the cause of the SVCS, the situation may be a medical emergency with no opportunity to establish a tissue diagnosis. In these cases, the most appropriate course may be to initiate empiric therapy prior to biopsy. The traditional empiric therapy is irradiation, with the daily dose governed by the presumed radiosensitivity of the tumor. After irradiation, respiratory deterioration from the apparent tracheal swelling may occur because of the inability of narrow lumens in children to accommodate edema and because of the greater degree of edema at onset, which is due to the rapid speed at which tumors grow in children. In these situations, a course of prednisone at 10 mg/m2 of body surface area 4 times per day may be necessary.