When compared to the general population, welders are at an increased risk of lung cancer (1). Cigarette smoking contributes to this risk. We present a case of pulmonary siderosis and bronchiolitis obliterans with organizing pneumonia (BOOP) presenting as bilateral pulmonary nodules in a welder with a significant history of cigarette smoking.
A 51-year-old welder, with a 90 pack-year history of cigarette smoking was found to have a right lower lobe pulmonary nodule on a chest radiograph during the work-up of kidney stones. He complained of occasional cough, and mild exertional dyspnea. He denied fevers, hemoptysis and weight loss. Physical examination was unremarkable except for mild wheezing on forced expiration. Pulmonary function tests showed a mild obstructive pattern and a normal diffusion capacity. Fungal serologies were negative. A chest computed tomography scan (CT) showed a 3 x 1.5 cm, irregular nodule in the right lower lobe, and a 1 cm nodule in the left upper lobe. No mediastinal or hilar adenopathy was present. Given the concern about possible lung cancer, a positron emission tomography (PET) scan with CT fusion images was done and demonstrated enhancement in both lesions. The patient underwent a thoracoscopic wedge resection of the right lower lobe. Gross pathology demonstrated a well-circumscribed, firm black lesion. Microscopic evaluation revealed pulmonary siderosis and bronchiolitis obliterans organizing pneumonia (BOOP). Two months after the surgery the patient returned for follow up. A repeat CT scan showed a 6-cm cavitating lesion in the left upper lobe, with associated ground-glass opacities in the same location of the previously noted nodule. A bronchoscopy with transbronchial lung biopsy was performed, revealing organizing pneumonia without tumor. Cultures from bronchoscopy grew Haemophilus parainfluenza. The patient was started on antibiotics, with clinical and radiologic improvement after one month.
Pulmonary siderosis is a benign condition that results from occupational exposure to inert metallic iron or iron oxides (2). Irregular, black particles of iron and hemosiderin accumulate in alveolar macrophages in the lung with a perivascular distribution and can produce radiologically visible nodules (3). The inflammatory finding of BOOP in this patient mimicked lung cancer on PET scan, leading to a surgical resection and diagnosis of pulmonary siderosis.
Lung biopsy is essential in the work-up of pulmonary nodules with PET scan enhancement. This is especially true in smokers with associated occupational exposure to iron. Benign lesions with active inflammation can have a high uptake in PET and are difficult to differentiate radiographically from malignancy. To our knowledge there have not been any reported cases of BOOP presenting as pulmonary nodules in welders.
J.L. Mendez, None.