False-positive CT and Thallium-201 SPECT Results in a Patient with Suspected Lung Cancer and Mediastinal Lymph Node Metastasis

We describe a patient with a final diagnosis of inflammatory change in which combined imaging results were strongly suggestive of lung cancer with mediastinal lymph node metastases. The patient, who was suspected of having a pulmonary lesion on chest radiography performed at a local hospital, was referred to our hospital. Contrast-enhanced computed tomography (CT) of the chest showed a small-sized opacity in the left upper lung and multiple mediastinal nodules. The largest mediastinal nodule, depicted at a pretracheal region, was 22 mm in size. Thallium-201 single photon emission computed tomography (SPECT) showed increased uptake in these lesions, which exhibited no remarkable washout of the tracer, supportive of the diagnosis of lung cancer with mediastinal lymph node metastasis. However, bronchoscopic and mediastinoscopic biopsy revealed no malignant cells or reactive lymph nodes, respectively. Therefore, no surgical procedure was performed after the biopsy. The patient has done well without evidence of malignancy for 21 months. Radiologists should be careful in the differential diagnosis of benign and malignant lesions even with combined imaging modalities.