ABSTRACT
Children who are receiving chemotherapy for malignant diseases are subject to a variety of pulmonary insults, many of which result in an interstitial pattern of disease. The malignancy itself may invade the pulmonary parenchyma, as part of primary disease or metastatic disease. The pulmonary lymphatics drain into the mediastinal nodes and then to the thoracic duct. Obstruction to lymph flow in the mediastinum may result in its retrograde flow with concomitant spread of tumor cells into the lung. Diffuse permeation through the pulmonary lymphatics is known as lymphangitis carcinomatosis. Tumor cells enter the pulmonary parenchyma by direct infiltration, lymphatic, hematogenous, transpleural and/or intrabronchial spread. If the tumor invades the bone marrow, hematogenous spread to the lung may occur, as in leukemia. Pulmonary disease is rare at initial presentation but is more commonly part of a relapse or generalized progression of disease, when it may play a more significant clinical role.
