The Medical Defense in Mesothelioma Cases

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The Medical Defense in Mesothelioma Cases

• Edward M. Slaughter
• Hawkins Parnell Thackston Young LLP
• 4514 Cole Avenue
• Dallas, TX 75205

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Overview

• Mesothelioma The Basics
• Stains
• Malignancy
• Tissue Digestion

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MESOTHELIOMA THE BASICS

• Pleural
• Usually caused by asbestos or some similar fiber,
  but not always
• Peritoneal
• Maybe caused by asbestos 50 or less
• Pericardial
• Rarely caused by asbestos
• Testicular mesothelioma
• Too uncomfortable to discuss

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Pleural Mesothelioma
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Pleural Mesothelioma

• Caused by prior radiation therapy at the site
• Other fibers
• Erionite (which is not just in Turkey)
• Taconite
• Maybe any fiber that that is biopersistent?
• Spontaneous or ideopathic

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Peritoneal Mesothelioma

• Often caused by some other inflammatory process
• Be on the lookout for
• Prior hernias
• Diverticulitis
• Hysterectomies
• Anything that leads to chronic inflammation

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Pericardial and Testicular

• If you ever see one we can talk about then.

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Types of mesothelioma

• Epithelial
• Sarcomatoid
• Biphasic

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Epithelial
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Sarcomatoid
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Biphasic
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Extremely Rare Diagnosis

• Desmoplastic
• Really just a rare subtype of sarcomatoid
• Hard to diagnose and easily confused with
  sarcomatoid adenocarcinoma
• Benign mesothelial hyperplasia
• Reactive process that looks like malignant
  mesothelioma
• Well differentiated papillary mesothelioma
• benign

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Desmoplastic
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Old men get Mesothelioma

• Female mesotheliomas are more often from another
  cause maybe 50-50
• Really young people usually dont have sufficient
  latency
• If the plaintiff is young look for other causes

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Take Away 1 Be Suspicious

• Mesothelioma in any location other than the
  pleura (by the lung) is very suspect
• Mesothelioma diagnosis with extra words is
  suspect (wdpm, hyperplasia, etc)
• Mesothelioma in young people and women is
  suspect.
• Be suspicious of the diagnosis in these cases.

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STAINS
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Stain Limitations

• Cant show if process is malignant or benign
• No single stain can definitively diagnose
  mesothelioma
• Glut-1 Caveat

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Specificity v. Sensitivity
EXAMPLE LeuM1 STAIN

• LeuM1 Stain Specific to Adenocarcinoma
• LeuM1 Stain Does Not Have High Sensitivity
  though, because does not react with all
  adenocarcinoma

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Other Common Stains

• Cytokeratins
• Glycoproteins
• Calretinin
• Thrombomodulin
• HBME-1
• Cadherins
• TTF-1

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Stains Used to Diagnose MesotheliomaCK5 -
CYTOKERATIN 5/6
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Stains Used to Diagnose MesotheliomaMESOTHELIN
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Stains Used to Diagnose MesotheliomaTHROMBOMODULI
N
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Stains Used to Diagnose MesotheliomaHBME-1
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Stains Used to Diagnose MesotheliomaCALRETININ
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Stains Used to Diagnose MesotheliomaWT-1
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Take Away 2 Stains are just a tool

• IHC stains are NEVER enough for a complete
  diagnosis
• They are positive stains and marginally positive
  stains
• No one stain is enough
• Stains cannot distinguish between malignant and
  benign mesotheliomas

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Diagnosing Malignancy

• Invasion
• Necrosis
• Clinical Correlation
• Other factors

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Stromal Invasion

• True stromal invasion is by far the most
  reliable
• criterion of mesothelial malignancy

Andrew Churg M.D., et al The Separation of Benign
and Malignant Mesothelial Proliferations The
American Journal of Surgical Pathology 24(9)1183
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Minimal Invasion
06/29/05 - Report of Dr. J.F. Legier
One single slide, 589D4, shows early invasive
disease with minimal invasion of fibrous stroma
by mesothelial clusters.
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6 Days Earlier Same Pathology
06/23/05 - Report of Dr. J.C. Maddox
based on the clinical history and imaging
studies that showed progression of the disease
(malignant mesothelioma on the left with
extensive mediastinal invasion) the patient
more likely than not had a malignant mesothelioma
that caused his death.
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And Another Opinion
05/21/07 - Report of I. Allen Feingold
Despite all of the above hisotpathological and
even immunohistochemical evidence against
malignancy in this case, it is important to
consider the observation of Dr. Robert Viggiano
who saw the patient in consultation and follow up
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Only Seen 10 Times

• Q Okay. And out of those 7- or 800 cases, how
  many times have you had a difficult diagnosis
  like this, where you had to compare this sort of
  a benign, reactive process to a malignant
  mesothelioma?
• A Maybe ten times.

Dr. Jacques Legier, pp. 72-73
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Clinical Correlation

• Just fancy talk for Did the patient seem like a
  man with mesothelioma?

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Necrosis

• Is there dead or dying tissue?

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Other Factors

• Read this
• Andrew Churg M.D., et al The Separation of
  Benign and Malignant Mesothelial Proliferations
  The American Journal of Surgical Pathology
  24(9)1183

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Take away 3 Not all Mesotheliomas are
Malignant

• Stains dont prove malignancy
• Invasion, Necrosis, Clinical Correlation do

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Tissue Selection

• A whole lung is ideal, but not necessary
• Autopsy, Pneumonectomy or biopsy
• Uninvolved tissue (not the tumor)
• The Bigger, The Better
• Multiple Sites
• But as little as a gram can be enough

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Results of Fiber Burden Analysis

• Evidence of Fiber Type
• Amount of Exposure
• Evidence of Other Exposures
• Helpful with Alternative Exposure Defenses

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Take Away 4 Digestion can be valuable

• To prove amphibole exposure
• To suggest an absence of chrysotile
• To prove a dose estimate

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All 4 Take Aways orThe Big Finale

• Be Suspicious of unusual mesotheliomas (extra
  words, people under 60, women)
• Stains are imperfect and dont prove malignancy -
  just differentiate between mesothelioma and other
  processes
• Malignancy has to be proven invasion, necrosis,
  clinical correlation
• Digestion can prove fiber type and dose, but not
  diagnosis