A 51-year-old man was admitted to the hospital for investigation of an asymptomatic right pleural effusion found on routine chest radiography (Figure 1). He was a current smoker (44 pack years) and had had tuberculosis at the age of 36, treated with first line drugs during one year. There was no other significant past medical history, and he was not taking any medication. His family history was irrelevant.
On physical examination, he was found to have clinical features of a small right-sided pleural effusion. Blood tests revealed mild chronic/inflammatory anemia (Hb 12.4 g/dL) and leukocytosis (13.3 x 109/L) without neutrophilia; the erythrocyte sedimentation rate (34 mm/h) and the C-reactive protein level (27.6 mg/L) were elevated. Chest radiography also showed left diaphragm retraction (Figure 1).
A computed tomography scan of the chest confirmed the presence of a right pleural effusion with associated pleural thickening and showed ipsilateral small basal pneumothorax; a pleural nodule was noted. On the left, a slight focal basal pleural thickening and upper lobe residual parenchymal changes were consistent with past tuberculosis (Figure 2). There was no evidence of tuberculosis reactivation, lung consolidation, nodules or masses, emphysema, or enlarged mediastinal lymph nodes.
 Through thoracentesis, a milky fluid was obtained, with very low pH (7.0). Empyema was suspected, and the patient was treated accordingly, with chest tube drainage and intravenous broad-spectrum antibiotics. Biochemical fluid analysis revealed an exudate (proteins 68.9 g/L; lactate dehydrogenase (LDH) 2986 U/L) with very low glucose (<10 mg/dL), high adenosine deaminase (201 U/L), and high cholesterol (205 mg/dL). On microscopic examination, cholesterol crystals were observed. Gram and Ziehl-Neelsen stains were negative. Pleural fluid cytology was normal, and blind pleural biopsies revealed fibrosis and marked inflammatory infiltrate without granulomas or neoplastic tissue. The diagnosis of pseudochylothorax was then established.
After careful anamnesis, the patient revealed complains of pain and swelling of multiple joints (hands, wrists, elbows, and knees) for some years. Subcutaneous nodules were seen on his left elbow and wrist (Figure 3), which proved to be RA nodules after surgical excision.
Rheumatoid factor was weakly positive (31.3 UI/mL), and anti-cyclic citrullinated peptide antibody was highly positive (>250 UA/mL). According to 2010 American College of Rheumatology/European League Against Rheumatism (ACR-EULAR) classification criteria, the patient was diagnosed with RA.
The antibiotics were stopped after seven days, the chest tube was removed, and the patient was discharged home. Immunosuppressive treatment was initiated at rheumatology outpatient clinic, with improvement of the articular symptoms. Two years after the diagnosis, the patient has no respiratory symptoms, pneumothorax has not recurred, and pleural effusion is stable without any additional therapy directed at the pleural space.