History of Present Illness
A 60-year-old Caucasian man was referred to our pulmonology clinic with a 1-month history of dyspnea and bilateral symmetrical arthralgias, mostly in the metacarpophalangeal joints and wrists. Chest radiography revealed right-sided pleural effusion without any lung parenchymal involvement ( Fig. 15.1 ).
Past Medical History
The patient had worked as a bricklayer and was a current heavy smoker (50 pack-year smoking history). He had a 9-year history of rheumatoid arthritis, which was being treated with methotrexate (15 mg/wk) and prednisone (10 mg/day). He denied any alcohol abuse.
Physical Examination and Early Clinical Findings
At admission, the patient was afebrile, oxygen saturation measured by pulse oximetry was 97% on room air, heart rate was 72 beats/min, and blood pressure was 125/75 mm Hg.
Physical examination revealed decreased breath sounds, decreased tactile fremitus, and dullness to percussion in the right lower pulmonary field. Bilateral swelling was evident in all the proximal interphalangeal and metacarpophalangeal joints of the hands and in the wrists.
Chest ultrasonography showed hypoechoic pleural effusion without any significant septation. Routine blood tests showed mild leukocytosis (white blood cell (WBC) count: 12,710/mm 3 ) with a normal differential count, associated to a slight increase in the inflammation indices (C-reactive protein [CRP]: 27.3 mg/L, normal values < 5 mg/L; erythrocytes sedimentation rate [ESR]: 38 mm/h, normal values < 22 mm/h). The electrolyte concentration values and the liver and kidney function test results were unremarkable.
Ultrasound-guided right thoracentesis was performed, and 1300 mL of cloudy nonmalodorous pleural fluid was drained ( Fig. 15.2 ). The procedure was well tolerated, and the pleural fluid was sent to the laboratory for analysis. The pleural fluid characteristics, which were measured by using a blood gas analyzer in the pulmonology ward, were available in a few minutes: pH 7.11, glucose 23 mg/dL.
In the subsequent days, biochemistry analyses revealed the presence of an exudative effusion (pleural fluid lactate dehydrogenase [LDH]: 805 units/L; serum LDH 401 units, ratio 2.0; pleural fluid protein 3.6 g/dL; and serum protein 3 g/dL, ratio 1.2). Culture of the pleural fluid yielded no growth. Smear microscopy and XpertMTB/RIF results were negative. The cytological analysis showed lymphocytosis (65% of lymphocytes) without malignant cells. Because of the gross appearance of the fluid, further analysis was requested. Triglyceride concentration was low (26 mg/dL) and no chylomicrons were detected. Cholesterol concentration was 247 mg/dL. The cholesterol/triglyceride ratio was 9.5. Cholesterol crystals were absent. On the basis of these findings, a diagnosis of pseudochylothorax was made.
Other laboratory investigations were then requested: human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) serological test results were unremarkable. The QuantiFERON-TB test result was positive.
Chest computed tomography (CT), performed after thoracentesis, showed the presence of thickened parietal pleura on the right, small-to-moderate residual right pleural effusion, and segmental atelectasis in the right lower lobe. Any other parenchymal abnormalities and mediastinal lymph node enlargement were not detected ( Fig. 15.3 ).
Because of the presence of pseudochylothorax of unknown etiology in a heavy smoker with rheumatoid arthritis and long-term immunosuppressive therapy, pleural biopsy was scheduled.
The patient underwent medical thoracoscopy, under local anesthesia (lidocaine) and moderate sedation (intravenous midazolam and fentanyl). The thoracoscopic investigation confirmed the presence of cloudy pleural fluid, which was immediately drained (1000 mL) ( Fig. 15.4 ).