Tim presented a young man with no medical history presenting with a chronic cough with intermittent trace hemoptsis. Other than this cough and mild shortness of breath when he exerted himself, this pt had no other symptoms. A CXR revealed bilateral pleural effusion, and upon thoracentesis, milky fluid drained out with an elevated triglyceride content consistent with a chylothorax. Subsequent biopsy of a lymph node revealed a diagnosis of follicular lymphoma!
Since we are talking about pleural effusion, Light’s Criteria will inevitably come up. For both real life (and boards!) purposes, know this criteria really well!
- SENSITIVE but NOT SPECIFIC for exudative effusions.
Any one of these criteria = exudative
- Fluid protein/Serum protein > 0.5
- Fluid LDH/Serum LDH > 0.6
- Fluid LDH > 2/3 upper limit of normal of serum LDH
False positive is possible in certain settings:
- Chronic diuretic use can falsely elevate fluid LDH (KNOW THIS)
- Transudative effusion that’s been sitting there chronically can appear exudative like
The following tests can help us distinguish between a falsely positive exudative effusion from a true exudative effusion:
- Pleural cholesterol > 45 mg/dL has high sensitivity and specificity for exudative effusions.
- Can also use serum albumin – fluid albumin < 1.2g/dL to confirm exudative effusion
Pleural Fluid Analysis: Clues
Upon performing a thoracentesis, certain characteristics can potentially give us some clues to the etiology of the effusion…
Fluid WBC Count
Fluid Predominant Myelocyte Type
Lastly, how do you diagnose a chylothorax and what are some potential causes?
- Definition: Triglyceride > 110 mg/dL = slam dunk
- 50 – 110: Less clear, cannot rule out, obtain liproprotein analysis. If presence of chylomicron is detected, likely chylothorax
- < 50: Less likely
- Malignant: Lymphomatous is most common, can also be other cancers i.e. lung, mediastinal mets, sarcoma, leukemia
- Non-malignant: Idiopathic, benign tumors, protein losing enteropathy, thoracic aortic aneurysm, TB, Sarcoid, amyloidosis, thyroid goiter, tuberous sclerosis, congestive heart failure, mitral stenosis
- Surgical is most common
- External trauma
- Trivial “trauma:” Stretching while yawning, coughing, hiccupping, sneezing (I’m not kidding)
Management of a malignant pleural effusion, as seen in this case, can be potentially challenging. After the patient was discharged, his pleural effusion on the right recurred within 3 days and completely filled up his right lung!
Several options are available for management of malignant pleural effusions. The decision is complicated and will goals of care discussion
- Indwelling pleural catheter
- Advantage: Pt managed, can drain at home
- Disadvantage: Catheter related complications
- Talc, slurry or poudrage, is the preferred agent. 60-90% success rate in reducing recurrence at 30 days.
- Doxycycline can also be used but not as popular any more
- Advantage: Eliminates the potential space for fluid reaccumulation
- Disadvantage: Pain, potential for surgical failure, invasive
- Combination: Talc + IPC