Chapter 5: Pulmonary Neoplasms and Masses

INTRODUCTION

Lung masses in children comprise a spectrum of neoplastic, developmental, and acquired lesions (Table 5-1). Most pulmonary masses in children are developmental or inflammatory. Blastomycosis can cause a large, solid lung mass that has imaging features similar to those of a neoplasm. Congenital bronchopulmonary malformations are important considerations in young children with a lung mass. Metastatic disease is the most common malignant lung lesion in children. The most common primary lung neoplasms are carcinoid, plasma cell granuloma, and pleuropulmonary blastoma. Children with immunodeficiency are at elevated risk for Epstein-Barr virus-related smooth muscle tumors, lymphoma, and lymphoproliferative disorders.^1–3

BENIGN LUNG MASSES

Plasma Cell Granuloma

Plasma cell granuloma is a benign parenchymal lung mass that may not be a true neoplasm. This lesion appears to develop as part of a reactive process following a pulmonary insult such as infection. However, some investigators consider it to be a low-grade fibrous histiocytoma. Plasma cell granuloma is also termed postinflammatory pseudotumor, inflammatory pseudotumor, and inflammatory myofibroblastic tumor. Other names that have been applied to this lesion in the medical literature include fibrous histiocytoma, fibroxanthoma, xanthogranuloma, and sclerosing hemangioma.

The varied terminology applied to plasma cell granulomas reflects the variability in the histological characteristics of these lesions. There is a mixture of fibroblasts, histiocytes, lymphocytes, and plasma cells. Those lesions with a predominance of plasma cells are most compatible with a chronic inflammatory reaction to an underlying unidentified agent or an exuberant reparative process in response to a pulmonary infection. This pattern has led to the terms plasma cell granuloma and postinflammatory pseudotumor. Some lesions, however, have a paucity of inflammatory cells, and the histological characteristics suggest a true neoplasm, such as benign "fibrous histiocytoma."^4,5

Plasma cell granuloma is the most common primary tumor of the lung in children. This lesion can occur in pediatric and adult patients of any age. Approximately one-third are identified in children; most pediatric patients with this lesion are older than 5 years of age. Plasma cell granulomas are often clinically silent; many are detected serendipitously on chest radiographs obtained for another medical indication. Potential clinical manifestations of the lesion include dyspnea, chest pain, hemoptysis, nonproductive cough, fever, and wheezing. Hypertrophic pulmonary osteoarthropathy can occur in associated with this lesion.⁶