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!

Light Criteria:

• 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 Color

Fluid WBC Count

Fluid Predominant Myelocyte Type

---

Lastly, how do you diagnose a chylothorax and what are some potential causes?

Chylothorax

• 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
• Non-traumatic
  • 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
• Traumatic
  • 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
• Pleurodesis
  • 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
• Pleurectomy