A single pulmonary rheumatoid nodule masquerading as malignancy.

We present a 54-year-old man, a heavy smoker, with clinical and laboratory evidence of familial hypercholesterolemia and an asymptomatic solitary pulmonary nodule (SPN) increasing in size on follow-up chest X-ray. Laboratory work-up revealed high titers of rheumatoid factor and the presence of acute phase reactants. Because of the patient's age and history of smoking, open lung biopsy was performed to rule out malignancy. The biopsy showed histological features compatible with a rheumatoid nodule. Identical features were noted in the histological examination of the subcutaneous nodule. Usually, rheumatoid nodules occur in patients with active, long-standing rheumatoid arthritis (RA) with other extra-articular manifestations. The presence of a single pulmonary rheumatoid nodule as the first manifestation of RA is extremely rare. Histologic proof is often required since pulmonary carcinoma can present an identical clinical and radiological pattern. The diagnostic work-up and the differential diagnosis of an SPN, particularly in a heavy smoker, is a common clinical request and remains a diagnostic challenge.