F-18 FDG PET/CT Findings in A Case of Multifocal Nodular Lymphoid Hyperplasia of the Lung

Pulmonary nodular lymphoid hyperplasia is a rare benign disease with polyclonal lymphoid proliferation. We describe a 67-year-old man with atypical manifestation of this disease with bilateral multifocal lesions including subcentimeter nodules and infiltrate, which showed only faint F-18 FDG uptake on PET/CT scan and spontaneous regression. Before obtaining histopathologic confirmation, the differential diagnosis of the multifocal lesions included metastases or malignant lymphoma, because of the history of extrathoracic malignancy, elevated serum interleukin-2 receptor, and temporal growing of the lesions. Histopathologic confirmation appears indispensable for the definitive diagnosis of pulmonary nodular lymphoid hyperplasia, as multifocal small lesions of malignancy, including mucosa-associated lymphoid tissue lymphoma and benign diseases such as plasmacytoma and inflammatory pseudotumor can also show only faint FDG uptake, with overlapping clinical and radiologic features.