Diagnosis
➤ Clinicians should perform an initial thoracentesis when patients present
with symptomatic pleural effusions and send pleural fluid for cytologic
examination for initial assessment for possible mesothelioma. (Strong
Recommendation; EB-I)
➤ In patients for whom antineoplastic treatment is planned, it is strongly
recommended that a thoracoscopic biopsy should be performed. (Strong
Recommendation; EB-H) This will:
a) enhance the information available for clinical staging
b) allow for histologic confirmation of diagnosis
c) enable more accurate determination of the pathologic subtype of mesothelioma
(epithelial, sarcomatoid, biphasic)
d) make material available for additional studies (e.g. molecular profiling ).
➤ When performing a thoracoscopic biopsy, the minimal number of incisions
(≤2) is recommended and should ideally be placed in areas that would
be used for subsequent definitive resection in order to avoid tumor
implantation into the chest wall. (Strong Recommendation; EB-H)
➤ In patients with suspected mesothelioma in whom treatment is planned, an
open pleural biopsy should be performed if the extent of tumor prevents
a thoracoscopic approach. The smallest incision possible is encouraged
(generally ≤6 cm is recommended). (Moderate Recommendation; EB-I)
➤ In patients who are not candidates for thoracoscopic biopsy or open pleural
biopsy, who also have a non-diagnostic thoracentesis or do not have a
pleural effusion, clinicians should perform a core needle biopsy of an
accessible lesion. (Strong Recommendation; EB-I)
➤ Cytologic evaluation of pleural fluid can be an initial screening test
for mesothelioma, but it is not a sufficiently sensitive diagnostic
test. Whenever definitive histologic diagnosis is needed, biopsies via
thoracoscopy or CT guidance offer a better opportunity to reach a definitive
diagnosis. (Strong Recommendation; EB-I)
➤ Histologic examination should be supplemented by immunohistochemistry
using selected markers expected to be positive in mesothelioma (e.g.,
calretinin, keratins 5/6, and nuclear WT1) as well as markers expected to
be negative in mesothelioma (e.g., CEA, EPCAM, Claudin 4, TTF-1). These
markers should be supplemented with other markers that address the
differential diagnosis in that particular situation. (Strong Recommendation;
EB-I)
➤ Mesothelioma should be reported as epithelial, sarcomatoid or biphasic,
because these subtypes have a clear prognostic significance. (Strong
Recommendation; EB-H)
