If a patient is asymptomatic or minimally symptomatic, bronchoscopy may be helpful in identifying and relieving a reversible cause of bronchial obstruction, such as a mucous plug or granulation tissue However, pulmonary lobectomy is most commonly required and may be needed acutely if symptoms are progressive The diseased lobe is evident at thoracotomy because of its overdistended state, often billowing out of the chest Lobectomy is curative if the cause of the obstruction is also relieved Congenital Pulmonary Arteriovenous Fistula Congenital pulmonary AV fistula is a congenitally occurring communication between a major pulmonary artery and a vein within the lung, usually with an aneurysmal sac Fistulae vary in size from a few millimeters to several centimeters and can be multiple At times, a systemic artery may also be involved Direct right-to-left shunting leads to hypoxemia, and the size of the fistula correlates with the degree of desaturation Clinical Recognition As the initial presentation of this disorder is frequently that of wheezing and desaturation, the child may be initially diagnosed with asthma Clubbing and cyanosis may demonstrate the hypoxemia Examination of the chest may reveal a palpable thrill or murmur If there are symptoms of hemoptysis and epistaxis, one may find telangiectasias or hemangiomas of the skin and mucous membranes Evaluation of the family may also reveal the presence of hereditary hemorrhagic telangiectasis (Rendu–Osler–Weber disease), which is present in more than half the patients with congenital pulmonary AV fistula Management Children who are symptomatic from this condition are best evaluated by CT scan, contrast echocardiography, perfusion scintigraphy, and arteriogram of the pulmonary artery and aorta Chest radiographs may demonstrate the aneurysmal areas as rounded or lobulated discrete lesions in the parenchyma Often, tortuous vessels trace from these rounded areas to the hilum Symptomatic patients should be admitted to the hospital while a definitive management course is decided Resection of the fistula, often involving lobectomy, is indicated if the lesion is localized, and may be curative Multiple small lesions may be amenable to embolization Unfortunately, some patients have such diffuse disease that such intervention is impossible Rare Lesions Unusual lung lesions encountered in the pediatric population include certain rare tumors and uncommon infections Rare solid tumors, often identified incidentally on radiographs, include primary sarcoma, pulmonary blastoma, hamartomas, and teratomas Fungal infections, including actinomycosis, histoplasmosis, mucormycosis, and coccidioidomycosis, may look like tumors on chest radiograph Atresia of the bronchus or pulmonary artery is rare and will produce differences in the density of the two lungs The reader is referred to texts of pulmonary medicine or thoracic surgery for further discussion MEDIASTINAL TUMORS CLINICAL PEARLS AND PITFALLS Symptoms of mediastinal lesions are frequently respiratory in nature Orthopnea is a worrisome sign, particularly with anterior mediastinal masses Such patients may experience respiratory or circulatory collapse with sedation or anesthesia Chest x-ray is the initial diagnostic study of choice and will demonstrate most significant mediastinal masses Anterior mediastinal tumors are frequently neoplastic and middle mediastinal tumors are often cystic Prompt surgical consultation may be needed in cases of respiratory distress or circulatory compromise Current Evidence At least one-third of all mediastinal lesions occur in children younger than 15 years of age The pathology in these cases is varied Half of these masses are symptomatic, and half of the symptomatic masses are malignant tumors, with the likelihood of malignancy increasing with the age of the patient More than 90% of asymptomatic masses are benign The mediastinum is commonly divided into anterior, superior, middle, and posterior compartments (Fig 124.11 ), and the location of a lesion can help to limit its differential diagnosis The superior mediastinal compartment contains germ cell tumors of the thymus, thymomas, and lymphangiomas The anterior compartment contains thymic tumors and lymphangiomas as well as lymphomas and teratomas Bronchogenic cysts in the area of the hilum are located in the middle mediastinum, and frequently have a cystic appearance on cross-sectional imaging Esophageal cysts and most neurogenic tumors, such as neuroblastomas and ganglioneuromas, are found in the posterior compartment Neurogenic tumors are the most common cause of mediastinal masses, with lymphomas and germ cell tumors being second and third in frequency Infection is an uncommon cause of mediastinal node enlargement, but when present, is frequently caused by histoplasmosis Thymic enlargement may mimic an anterior mediastinal mass FIGURE 124.11 Mediastinal tumors in children Differential diagnosis is based on anatomic location within the mediastinum Goal of Treatment Since the meadiastinum is a limited and confined space, lesions in this anatomic area can cause respiratory and circulatory compromise, which may be the presenting symptoms Prompt identification of a space-occupying mediastinal mass and an awareness of the relevant anatomy are critical These patients require careful attention and early consultation with appropriate specialists for complete workup and expeditious treatment Clinical Considerations Clinical Recognition Mediastinal masses frequently present with chest pain or respiratory symptoms as a result of airway compression Patients may present with cough, wheezing, recurrent respiratory infections, bronchitis, atelectasis, and hemoptysis Dysphagia and hematemesis may occur with compression of the esophagus Superior vena cava syndrome is a rare complication, usually in association with a rapidly growing tumor Orthopnea may occur with vascular compression If the recurrent laryngeal nerve is compressed as a result of the mass, hoarseness and inspiratory stridor may result Spinal cord compression and vertebral erosion can be seen with a posterior mediastinal tumor A careful history may reveal more subtle symptoms, and families should be queried specifically about fever, chills, weight loss, and night sweats Physical examination should be thorough It is important to focus on a careful respiratory and cardiac examination, evaluation of the head and neck for palpable masses or venous distention, palpation of the abdomen for organomegaly or masses, and examination of the various nodal basins for adenopathy Solid Mediastinal Masses Children with tumors of the anterior or superior mediastinum should be admitted to an inpatient ward for urgent evaluation because these tumors may pose an immediate threat to life CT scan or MRI of the chest is generally needed to supplement plain radiographs, in order to further define the location and extent of the mass, and to potentially provide details that may help establish the diagnosis Much of the management depends upon whether the lesion is cystic or solid Solid masses raise concern for oncologic pathology, particularly if located in the anterior mediastinum, and imaging may be very helpful in aiding diagnosis In the appropriate clinical setting, tumor markers should be obtained, including serum alpha fetoprotein (AFP) and beta-human chorionic gonadotropin (bHCG) levels, and urine catecholamine and metanephrine levels Lymphomas and teratomas are the most common mediastinal tumors in children, with other solid masses occurring more rarely Thymomas comprise less than 1% of mediastinal tumors in children, with multimodal therapy the mainstay Benign thymic hyperplasia typically does not cause respiratory compromise, but rapid enlargement often warrants intervention, such as steroid therapy or resection When biopsy of a large mediastinal mass is necessary, the logistics of the procedure require careful, thoughtful evaluation, ideally involving the pediatrician or emergency clinician, surgeon, oncologist, and anesthesiologist Airway and cardiac compression by large mediastinal masses can be significant Large mediastinal masses should be evaluated by CT scan of the chest to assess the presence and extent of tracheal compression MRI may be a better diagnostic modality for posterior mediastinal masses because many of them are neurogenic in origin and may have extension into the spinal canal An echocardiogram should also be obtained prior to surgery, to assess the extent of mediastinal shift and the degree of atrial or ventricular compression by the mass Delivery of general anesthesia may lead to occlusion of the thoracic trachea by the tumor This situation can be challenging to manage; passage of a rigid bronchoscope ... logistics of the procedure require careful, thoughtful evaluation, ideally involving the pediatrician or emergency clinician, surgeon, oncologist, and anesthesiologist Airway and cardiac compression... produce differences in the density of the two lungs The reader is referred to texts of pulmonary medicine or thoracic surgery for further discussion MEDIASTINAL TUMORS CLINICAL PEARLS AND PITFALLS...Unusual lung lesions encountered in the pediatric population include certain rare tumors and uncommon infections Rare solid tumors, often