[Pseudotumoral pulmonary AL amyloidosis]. / Amylose AL pulmonaire de forme pseudo-tumorale.

INTRODUCTION: Thoracic involvement in amyloidosis is rare. An isolated pseudotumor without extra-thoracic disease suggests a malignant process. We present the case of a patient with pseudonodular AL amyloidosis, confirmed by lobar lung resection. CASE REPORT: A 57-year-old woman, with a 25-pack-year smoking history, presented with a nodular opacity on chest x-ray. Physical examination was normal. Thoracic CT-scan revealed an isolated spiculated nodule in the right upper lobe. A whole body positron emission tomography (PET) scan revealed high FDG activity in this nodule, without evidence of metastatic disease. Bronchoscopy was negative. Lobectomy revealed lambda L-chain amyloidosis. Investigation for systemic extension was negative. Follow up has been unremarkable. CONCLUSION: A spiculated lung nodule on conventional imaging (radiography, scanner) is cancer until proven otherwise. The use of PET scan in this context is sensitive but not specific. Definitive diagnosis must be obtained by histological examination. Nodular lung amyloidosis must be included in the differential diagnosis of lung nodules and false-positive FDG PET.